(SQL SERVER) (ORACLE) (ACCESS)(POSTGRE SQL)四种数据库操作C#代码

将对这四种数据库的操作封装到了2个类中可以拷贝过去直接使用。

   public sealed class OleDbClass

    {

        #region private utility methods & constructors



        //Since this class provides only static methods, make the default constructor private to prevent 

        //instances from being created with "new SqlHelper()".

        private OleDbClass() { }







        /// <summary>

        /// This method is used to attach array of SqlParameters to a SqlCommand.

        /// 

        /// This method will assign a value of DbNull to any parameter with a direction of

        /// InputOutput and a value of null.  

        /// 

        /// This behavior will prevent default values from being used, but

        /// this will be the less common case than an intended pure output parameter (derived as InputOutput)

        /// where the user provided no input value.

        /// </summary>

        /// <param name="command">The command to which the parameters will be added</param>

        /// <param name="commandParameters">an array of SqlParameters tho be added to command</param>

        private static void AttachParameters(SqlCommand command, SqlParameter[] commandParameters)

        {

            foreach (SqlParameter p in commandParameters)

            {

                //check for derived output value with no value assigned

                if ((p.Direction == ParameterDirection.InputOutput) && (p.Value == null))

                {

                    p.Value = DBNull.Value;

                }



                command.Parameters.Add(p);

            }

        }



        /// <summary>

        /// This method assigns an array of values to an array of SqlParameters.

        /// </summary>

        /// <param name="commandParameters">array of SqlParameters to be assigned values</param>

        /// <param name="parameterValues">array of objects holding the values to be assigned</param>

        private static void AssignParameterValues(SqlParameter[] commandParameters, object[] parameterValues)

        {

            if ((commandParameters == null) || (parameterValues == null))

            {

                //do nothing if we get no data

                return;

            }



            // we must have the same number of values as we pave parameters to put them in

            if (commandParameters.Length != parameterValues.Length)

            {

                throw new ArgumentException("Parameter count does not match Parameter Value count.");

            }



            //iterate through the SqlParameters, assigning the values from the corresponding position in the 

            //value array

            for (int i = 0, j = commandParameters.Length; i < j; i++)

            {

                commandParameters[i].Value = parameterValues[i];

            }

        }



        /// <summary>

        /// This method opens (if necessary) and assigns a connection, transaction, command type and parameters 

        /// to the provided command.

        /// </summary>

        /// <param name="command">the SqlCommand to be prepared</param>

        /// <param name="connection">a valid SqlConnection, on which to execute this command</param>

        /// <param name="transaction">a valid SqlTransaction, or 'null'</param>

        /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>

        /// <param name="commandText">the stored procedure name or T-SQL command</param>

        /// <param name="commandParameters">an array of SqlParameters to be associated with the command or 'null' if no parameters are required</param>

        private static void PrepareCommand(SqlCommand command, SqlConnection connection, SqlTransaction transaction, CommandType commandType, 

string commandText, SqlParameter[] commandParameters)

        {

            //if the provided connection is not open, we will open it

            if (connection.State != ConnectionState.Open)

            {

                connection.Open();

            }



            //associate the connection with the command

            command.Connection = connection;



            //set the command text (stored procedure name or SQL statement)

            command.CommandText = commandText;



            //if we were provided a transaction, assign it.

            if (transaction != null)

            {

                command.Transaction = transaction;

            }



            //set the command type

            command.CommandType = commandType;



            //attach the command parameters if they are provided

            if (commandParameters != null)

            {

                AttachParameters(command, commandParameters);

            }



            return;

        }





        #endregion private utility methods & constructors



        #region ExecuteNonQuery



        /// <summary>

        /// Execute a SqlCommand (that returns no resultset and takes no parameters) against the database specified in 

        /// the connection string. 

        /// </summary>

        /// <remarks>

        /// e.g.:  

        ///  int result = ExecuteNonQuery(connString, CommandType.StoredProcedure, "PublishOrders");

        /// </remarks>

        /// <param name="connectionString">a valid connection string for a SqlConnection</param>

        /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>

        /// <param name="commandText">the stored procedure name or T-SQL command</param>

        /// <returns>an int representing the number of rows affected by the command</returns>

        public static int ExecuteNonQuery(string connectionString, CommandType commandType, string commandText)

        {

            //pass through the call providing null for the set of SqlParameters

            return ExecuteNonQuery(connectionString, commandType, commandText, (SqlParameter[])null);

        }



        /// <summary>

        /// Execute a SqlCommand (that returns no resultset) against the database specified in the connection string 

        /// using the provided parameters.

        /// </summary>

        /// <remarks>

        /// e.g.:  

        ///  int result = ExecuteNonQuery(connString, CommandType.StoredProcedure, "PublishOrders", new SqlParameter("@prodid", 24));

        /// </remarks>

        /// <param name="connectionString">a valid connection string for a SqlConnection</param>

        /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>

        /// <param name="commandText">the stored procedure name or T-SQL command</param>

        /// <param name="commandParameters">an array of SqlParamters used to execute the command</param>

        /// <returns>an int representing the number of rows affected by the command</returns>

        public static int ExecuteNonQuery(string connectionString, CommandType commandType, string commandText, params SqlParameter[] commandParameters)

        {

            //create & open a SqlConnection, and dispose of it after we are done.

            using (SqlConnection cn = new SqlConnection(connectionString))

            {

                cn.Open();



                //call the overload that takes a connection in place of the connection string

                return ExecuteNonQuery(cn, commandType, commandText, commandParameters);

            }

        }



        /// <summary>

        /// Execute a stored procedure via a SqlCommand (that returns no resultset) against the database specified in 

        /// the connection string using the provided parameter values.  This method will query the database to discover the parameters for the 

        /// stored procedure (the first time each stored procedure is called), and assign the values based on parameter order.

        /// </summary>

        /// <remarks>

        /// This method provides no access to output parameters or the stored procedure's return value parameter.

        /// 

        /// e.g.:  

        ///  int result = ExecuteNonQuery(connString, "PublishOrders", 24, 36);

        /// </remarks>

        /// <param name="connectionString">a valid connection string for a SqlConnection</param>

        /// <param name="spName">the name of the stored prcedure</param>

        /// <param name="parameterValues">an array of objects to be assigned as the input values of the stored procedure</param>

        /// <returns>an int representing the number of rows affected by the command</returns>

        public static int ExecuteNonQuery(string connectionString, string spName, params object[] parameterValues)

        {

            //if we receive parameter values, we need to figure out where they go

            if ((parameterValues != null) && (parameterValues.Length > 0))

            {

                //pull the parameters for this stored procedure from the parameter cache (or discover them & populate the cache)

                SqlParameter[] commandParameters = SqlParameterClass.GetSpParameterSet(connectionString, spName);



                //assign the provided values to these parameters based on parameter order

                AssignParameterValues(commandParameters, parameterValues);



                //call the overload that takes an array of SqlParameters

                return ExecuteNonQuery(connectionString, CommandType.StoredProcedure, spName, commandParameters);

            }

            //otherwise we can just call the SP without params

            else

            {

                return ExecuteNonQuery(connectionString, CommandType.StoredProcedure, spName);

            }

        }



        /// <summary>

        /// Execute a SqlCommand (that returns no resultset and takes no parameters) against the provided SqlConnection. 

        /// </summary>

        /// <remarks>

        /// e.g.:  

        ///  int result = ExecuteNonQuery(conn, CommandType.StoredProcedure, "PublishOrders");

        /// </remarks>

        /// <param name="connection">a valid SqlConnection</param>

        /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>

        /// <param name="commandText">the stored procedure name or T-SQL command</param>

        /// <returns>an int representing the number of rows affected by the command</returns>

        public static int ExecuteNonQuery(SqlConnection connection, CommandType commandType, string commandText)

        {

            //pass through the call providing null for the set of SqlParameters

            return ExecuteNonQuery(connection, commandType, commandText, (SqlParameter[])null);

        }



        /// <summary>

        /// Execute a SqlCommand (that returns no resultset) against the specified SqlConnection 

        /// using the provided parameters.

        /// </summary>

        /// <remarks>

        /// e.g.:  

        ///  int result = ExecuteNonQuery(conn, CommandType.StoredProcedure, "PublishOrders", new SqlParameter("@prodid", 24));

        /// </remarks>

        /// <param name="connection">a valid SqlConnection</param>

        /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>

        /// <param name="commandText">the stored procedure name or T-SQL command</param>

        /// <param name="commandParameters">an array of SqlParamters used to execute the command</param>

        /// <returns>an int representing the number of rows affected by the command</returns>

        public static int ExecuteNonQuery(SqlConnection connection, CommandType commandType, string commandText, params SqlParameter[] commandParameters)

        {

            //create a command and prepare it for execution

            SqlCommand cmd = new SqlCommand();

            PrepareCommand(cmd, connection, (SqlTransaction)null, commandType, commandText, commandParameters);



            //finally, execute the command.

            int retval = cmd.ExecuteNonQuery();



            // detach the SqlParameters from the command object, so they can be used again.

            cmd.Parameters.Clear();

            return retval;

        }



        /// <summary>

        /// Execute a stored procedure via a SqlCommand (that returns no resultset) against the specified SqlConnection 

        /// using the provided parameter values.  This method will query the database to discover the parameters for the 

        /// stored procedure (the first time each stored procedure is called), and assign the values based on parameter order.

        /// </summary>

        /// <remarks>

        /// This method provides no access to output parameters or the stored procedure's return value parameter.

        /// 

        /// e.g.:  

        ///  int result = ExecuteNonQuery(conn, "PublishOrders", 24, 36);

        /// </remarks>

        /// <param name="connection">a valid SqlConnection</param>

        /// <param name="spName">the name of the stored procedure</param>

        /// <param name="parameterValues">an array of objects to be assigned as the input values of the stored procedure</param>

        /// <returns>an int representing the number of rows affected by the command</returns>

        public static int ExecuteNonQuery(SqlConnection connection, string spName, params object[] parameterValues)

        {

            //if we receive parameter values, we need to figure out where they go

            if ((parameterValues != null) && (parameterValues.Length > 0))

            {

                //pull the parameters for this stored procedure from the parameter cache (or discover them & populate the cache)

                SqlParameter[] commandParameters = SqlParameterClass.GetSpParameterSet(connection.ConnectionString, spName);



                //assign the provided values to these parameters based on parameter order

                AssignParameterValues(commandParameters, parameterValues);



                //call the overload that takes an array of SqlParameters

                return ExecuteNonQuery(connection, CommandType.StoredProcedure, spName, commandParameters);

            }

            //otherwise we can just call the SP without params

            else

            {

                return ExecuteNonQuery(connection, CommandType.StoredProcedure, spName);

            }

        }



        /// <summary>

        /// Execute a SqlCommand (that returns no resultset and takes no parameters) against the provided SqlTransaction. 

        /// </summary>

        /// <remarks>

        /// e.g.:  

        ///  int result = ExecuteNonQuery(trans, CommandType.StoredProcedure, "PublishOrders");

        /// </remarks>

        /// <param name="transaction">a valid SqlTransaction</param>

        /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>

        /// <param name="commandText">the stored procedure name or T-SQL command</param>

        /// <returns>an int representing the number of rows affected by the command</returns>

        public static int ExecuteNonQuery(SqlTransaction transaction, CommandType commandType, string commandText)

        {

            //pass through the call providing null for the set of SqlParameters

            return ExecuteNonQuery(transaction, commandType, commandText, (SqlParameter[])null);

        }



        /// <summary>

        /// Execute a SqlCommand (that returns no resultset) against the specified SqlTransaction

        /// using the provided parameters.

        /// </summary>

        /// <remarks>

        /// e.g.:  

        ///  int result = ExecuteNonQuery(trans, CommandType.StoredProcedure, "GetOrders", new SqlParameter("@prodid", 24));

        /// </remarks>

        /// <param name="transaction">a valid SqlTransaction</param>

        /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>

        /// <param name="commandText">the stored procedure name or T-SQL command</param>

        /// <param name="commandParameters">an array of SqlParamters used to execute the command</param>

        /// <returns>an int representing the number of rows affected by the command</returns>

        public static int ExecuteNonQuery(SqlTransaction transaction, CommandType commandType, string commandText, 

params SqlParameter[] commandParameters)

        {

            //create a command and prepare it for execution

            SqlCommand cmd = new SqlCommand();

            PrepareCommand(cmd, transaction.Connection, transaction, commandType, commandText, commandParameters);



            //finally, execute the command.

            int retval = cmd.ExecuteNonQuery();



            // detach the SqlParameters from the command object, so they can be used again.

            cmd.Parameters.Clear();

            return retval;

        }



        /// <summary>

        /// Execute a stored procedure via a SqlCommand (that returns no resultset) against the specified 

        /// SqlTransaction using the provided parameter values.  This method will query the database to discover the parameters for the 

        /// stored procedure (the first time each stored procedure is called), and assign the values based on parameter order.

        /// </summary>

        /// <remarks>

        /// This method provides no access to output parameters or the stored procedure's return value parameter.

        /// 

        /// e.g.:  

        ///  int result = ExecuteNonQuery(conn, trans, "PublishOrders", 24, 36);

        /// </remarks>

        /// <param name="transaction">a valid SqlTransaction</param>

        /// <param name="spName">the name of the stored procedure</param>

        /// <param name="parameterValues">an array of objects to be assigned as the input values of the stored procedure</param>

        /// <returns>an int representing the number of rows affected by the command</returns>

        public static int ExecuteNonQuery(SqlTransaction transaction, string spName, params object[] parameterValues)

        {

            //if we receive parameter values, we need to figure out where they go

            if ((parameterValues != null) && (parameterValues.Length > 0))

            {

                //pull the parameters for this stored procedure from the parameter cache (or discover them & populate the cache)

                SqlParameter[] commandParameters = SqlParameterClass.GetSpParameterSet(transaction.Connection.ConnectionString, spName);



                //assign the provided values to these parameters based on parameter order

                AssignParameterValues(commandParameters, parameterValues);



                //call the overload that takes an array of SqlParameters

                return ExecuteNonQuery(transaction, CommandType.StoredProcedure, spName, commandParameters);

            }

            //otherwise we can just call the SP without params

            else

            {

                return ExecuteNonQuery(transaction, CommandType.StoredProcedure, spName);

            }

        }





        #endregion ExecuteNonQuery



        #region ExecuteDataSet



        /// <summary>

        /// Execute a SqlCommand (that returns a resultset and takes no parameters) against the database specified in 

        /// the connection string. 

        /// </summary>

        /// <remarks>

        /// e.g.:  

        ///  DataSet ds = ExecuteDataset(connString, CommandType.StoredProcedure, "GetOrders");

        /// </remarks>

        /// <param name="connectionString">a valid connection string for a SqlConnection</param>

        /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>

        /// <param name="commandText">the stored procedure name or T-SQL command</param>

        /// <returns>a dataset containing the resultset generated by the command</returns>

        public static DataSet ExecuteDataset(string connectionString, CommandType commandType, string commandText)

        {

            //pass through the call providing null for the set of SqlParameters

            return ExecuteDataset(connectionString, commandType, commandText, (SqlParameter[])null);

        }



        /// <summary>

        /// Execute a SqlCommand (that returns a resultset) against the database specified in the connection string 

        /// using the provided parameters.

        /// </summary>

        /// <remarks>

        /// e.g.:  

        ///  DataSet ds = ExecuteDataset(connString, CommandType.StoredProcedure, "GetOrders", new SqlParameter("@prodid", 24));

        /// </remarks>

        /// <param name="connectionString">a valid connection string for a SqlConnection</param>

        /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>

        /// <param name="commandText">the stored procedure name or T-SQL command</param>

        /// <param name="commandParameters">an array of SqlParamters used to execute the command</param>

        /// <returns>a dataset containing the resultset generated by the command</returns>

        public static DataSet ExecuteDataset(string connectionString, CommandType commandType, string commandText,

 params SqlParameter[] commandParameters)

        {

            //create & open a SqlConnection, and dispose of it after we are done.

            using (SqlConnection cn = new SqlConnection(connectionString))

            {

                cn.Open();



                //call the overload that takes a connection in place of the connection string

                return ExecuteDataset(cn, commandType, commandText, commandParameters);

            }

        }



        public static DataTable ExecuteDataset_oracle(string connectionString, CommandType commandType, string commandText)

        {



            DataTable Dt = new DataTable();

            using (OracleConnection mConn = new OracleConnection(connectionString))

            {





                mConn.Open();





                OracleCommand cmd = new OracleCommand(commandText, mConn);



                OracleDataAdapter dap = new OracleDataAdapter(cmd);

                dap.Fill(Dt);



                mConn.Close();

            }

            return Dt;

        }



        public static DataTable ExecuteDataset_PostgreSQL(string connectionString, CommandType commandType, string commandText)

        {

           DataTable Dt = new DataTable();

            try

            {

                using (NpgsqlConnection mConn = new NpgsqlConnection(connectionString))

                {



                    NpgsqlCommand comm = new NpgsqlCommand(commandText, mConn);



                    mConn.Open();

                    

                    NpgsqlDataAdapter sda = new NpgsqlDataAdapter();

                    sda.SelectCommand = comm;



                    sda.Fill(Dt);



                    mConn.Close();

                }

            }

            catch (Exception)

            {

                return null;

            }

            return Dt;



        }





        public static int Execute_PostgreSQL(string connectionString, CommandType commandType, string commandText)

        {

            int ret;

            try

            {

                using (NpgsqlConnection mConn = new NpgsqlConnection(connectionString))

                {



                    NpgsqlCommand comm = new NpgsqlCommand(commandText, mConn);

                    try

                    {

                        mConn.Open();

                    }

                    catch

                    {

                        return -2;

                    }

                    ret = comm.ExecuteNonQuery();

                    mConn.Close();

                }

            }

            catch (Exception)

            {

                return 0;

            }

            return ret;

        }



        public static DataTable ExecuteDataset_oracle(string connectionString, string commandText)

        {



            DataTable Dt = new DataTable();

            using (OracleConnection mConn = new OracleConnection(connectionString))

            {





                mConn.Open();





                OracleCommand cmd = new OracleCommand(commandText, mConn);



                OracleDataAdapter dap = new OracleDataAdapter(cmd);

                dap.Fill(Dt);



                mConn.Close();

            }

            return Dt;

        }



        /// <summary>

        /// Execute a stored procedure via a SqlCommand (that returns a resultset) against the database specified in 

        /// the connection string using the provided parameter values.  This method will query the database to discover the parameters for the 

        /// stored procedure (the first time each stored procedure is called), and assign the values based on parameter order.

        /// </summary>

        /// <remarks>

        /// This method provides no access to output parameters or the stored procedure's return value parameter.

        /// 

        /// e.g.:  

        ///  DataSet ds = ExecuteDataset(connString, "GetOrders", 24, 36);

        /// </remarks>

        /// <param name="connectionString">a valid connection string for a SqlConnection</param>

        /// <param name="spName">the name of the stored procedure</param>

        /// <param name="parameterValues">an array of objects to be assigned as the input values of the stored procedure</param>

        /// <returns>a dataset containing the resultset generated by the command</returns>

        public static DataSet ExecuteDataset(string connectionString, string spName, params object[] parameterValues)

        {

            //if we receive parameter values, we need to figure out where they go

            if ((parameterValues != null) && (parameterValues.Length > 0))

            {

                //pull the parameters for this stored procedure from the parameter cache (or discover them & populate the cache)

                SqlParameter[] commandParameters = SqlParameterClass.GetSpParameterSet(connectionString, spName);



                //assign the provided values to these parameters based on parameter order

                AssignParameterValues(commandParameters, parameterValues);



                //call the overload that takes an array of SqlParameters

                return ExecuteDataset(connectionString, CommandType.StoredProcedure, spName, commandParameters);

            }

            //otherwise we can just call the SP without params

            else

            {

                return ExecuteDataset(connectionString, CommandType.StoredProcedure, spName);

            }

        }



        /// <summary>

        /// Execute a SqlCommand (that returns a resultset and takes no parameters) against the provided SqlConnection. 

        /// </summary>

        /// <remarks>

        /// e.g.:  

        ///  DataSet ds = ExecuteDataset(conn, CommandType.StoredProcedure, "GetOrders");

        /// </remarks>

        /// <param name="connection">a valid SqlConnection</param>

        /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>

        /// <param name="commandText">the stored procedure name or T-SQL command</param>

        /// <returns>a dataset containing the resultset generated by the command</returns>

        public static DataSet ExecuteDataset(SqlConnection connection, CommandType commandType, string commandText)

        {

            //pass through the call providing null for the set of SqlParameters

            return ExecuteDataset(connection, commandType, commandText, (SqlParameter[])null);

        }



        /// <summary>

        /// Execute a SqlCommand (that returns a resultset) against the specified SqlConnection 

        /// using the provided parameters.

        /// </summary>

        /// <remarks>

        /// e.g.:  

        ///  DataSet ds = ExecuteDataset(conn, CommandType.StoredProcedure, "GetOrders", new SqlParameter("@prodid", 24));

        /// </remarks>

        /// <param name="connection">a valid SqlConnection</param>

        /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>

        /// <param name="commandText">the stored procedure name or T-SQL command</param>

        /// <param name="commandParameters">an array of SqlParamters used to execute the command</param>

        /// <returns>a dataset containing the resultset generated by the command</returns>

        public static DataSet ExecuteDataset(SqlConnection connection, CommandType commandType, string commandText, 

params SqlParameter[] commandParameters)

        {

            //create a command and prepare it for execution

            SqlCommand cmd = new SqlCommand();

            PrepareCommand(cmd, connection, (SqlTransaction)null, commandType, commandText, commandParameters);



            //create the DataAdapter & DataSet

            SqlDataAdapter da = new SqlDataAdapter(cmd);

            DataSet ds = new DataSet();



            //fill the DataSet using default values for DataTable names, etc.

            da.Fill(ds);



            // detach the SqlParameters from the command object, so they can be used again.			

            cmd.Parameters.Clear();



            //return the dataset

            return ds;

        }



        /// <summary>

        /// Execute a stored procedure via a SqlCommand (that returns a resultset) against the specified SqlConnection 

        /// using the provided parameter values.  This method will query the database to discover the parameters for the 

        /// stored procedure (the first time each stored procedure is called), and assign the values based on parameter order.

        /// </summary>

        /// <remarks>

        /// This method provides no access to output parameters or the stored procedure's return value parameter.

        /// 

        /// e.g.:  

        ///  DataSet ds = ExecuteDataset(conn, "GetOrders", 24, 36);

        /// </remarks>

        /// <param name="connection">a valid SqlConnection</param>

        /// <param name="spName">the name of the stored procedure</param>

        /// <param name="parameterValues">an array of objects to be assigned as the input values of the stored procedure</param>

        /// <returns>a dataset containing the resultset generated by the command</returns>

        public static DataSet ExecuteDataset(SqlConnection connection, string spName, params object[] parameterValues)

        {

            //if we receive parameter values, we need to figure out where they go

            if ((parameterValues != null) && (parameterValues.Length > 0))

            {

                //pull the parameters for this stored procedure from the parameter cache (or discover them & populate the cache)

                SqlParameter[] commandParameters = SqlParameterClass.GetSpParameterSet(connection.ConnectionString, spName);



                //assign the provided values to these parameters based on parameter order

                AssignParameterValues(commandParameters, parameterValues);



                //call the overload that takes an array of SqlParameters

                return ExecuteDataset(connection, CommandType.StoredProcedure, spName, commandParameters);

            }

            //otherwise we can just call the SP without params

            else

            {

                return ExecuteDataset(connection, CommandType.StoredProcedure, spName);

            }

        }



        /// <summary>

        /// Execute a SqlCommand (that returns a resultset and takes no parameters) against the provided SqlTransaction. 

        /// </summary>

        /// <remarks>

        /// e.g.:  

        ///  DataSet ds = ExecuteDataset(trans, CommandType.StoredProcedure, "GetOrders");

        /// </remarks>

        /// <param name="transaction">a valid SqlTransaction</param>

        /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>

        /// <param name="commandText">the stored procedure name or T-SQL command</param>

        /// <returns>a dataset containing the resultset generated by the command</returns>

        public static DataSet ExecuteDataset(SqlTransaction transaction, CommandType commandType, string commandText)

        {

            //pass through the call providing null for the set of SqlParameters

            return ExecuteDataset(transaction, commandType, commandText, (SqlParameter[])null);

        }



        /// <summary>

        /// Execute a SqlCommand (that returns a resultset) against the specified SqlTransaction

        /// using the provided parameters.

        /// </summary>

        /// <remarks>

        /// e.g.:  

        ///  DataSet ds = ExecuteDataset(trans, CommandType.StoredProcedure, "GetOrders", new SqlParameter("@prodid", 24));

        /// </remarks>

        /// <param name="transaction">a valid SqlTransaction</param>

        /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>

        /// <param name="commandText">the stored procedure name or T-SQL command</param>

        /// <param name="commandParameters">an array of SqlParamters used to execute the command</param>

        /// <returns>a dataset containing the resultset generated by the command</returns>

        public static DataSet ExecuteDataset(SqlTransaction transaction, CommandType commandType, string commandText,

 params SqlParameter[] commandParameters)

        {

            //create a command and prepare it for execution

            SqlCommand cmd = new SqlCommand();

            PrepareCommand(cmd, transaction.Connection, transaction, commandType, commandText, commandParameters);



            //create the DataAdapter & DataSet

            SqlDataAdapter da = new SqlDataAdapter(cmd);

            DataSet ds = new DataSet();



            //fill the DataSet using default values for DataTable names, etc.

            da.Fill(ds);



            // detach the SqlParameters from the command object, so they can be used again.

            cmd.Parameters.Clear();



            //return the dataset

            return ds;

        }



        /// <summary>

        /// Execute a stored procedure via a SqlCommand (that returns a resultset) against the specified 

        /// SqlTransaction using the provided parameter values.  This method will query the database to discover the parameters for the 

        /// stored procedure (the first time each stored procedure is called), and assign the values based on parameter order.

        /// </summary>

        /// <remarks>

        /// This method provides no access to output parameters or the stored procedure's return value parameter.

        /// 

        /// e.g.:  

        ///  DataSet ds = ExecuteDataset(trans, "GetOrders", 24, 36);

        /// </remarks>

        /// <param name="transaction">a valid SqlTransaction</param>

        /// <param name="spName">the name of the stored procedure</param>

        /// <param name="parameterValues">an array of objects to be assigned as the input values of the stored procedure</param>

        /// <returns>a dataset containing the resultset generated by the command</returns>

        public static DataSet ExecuteDataset(SqlTransaction transaction, string spName, params object[] parameterValues)

        {

            //if we receive parameter values, we need to figure out where they go

            if ((parameterValues != null) && (parameterValues.Length > 0))

            {

                //pull the parameters for this stored procedure from the parameter cache (or discover them & populate the cache)

                SqlParameter[] commandParameters = SqlParameterClass.GetSpParameterSet(transaction.Connection.ConnectionString, spName);



                //assign the provided values to these parameters based on parameter order

                AssignParameterValues(commandParameters, parameterValues);



                //call the overload that takes an array of SqlParameters

                return ExecuteDataset(transaction, CommandType.StoredProcedure, spName, commandParameters);

            }

            //otherwise we can just call the SP without params

            else

            {

                return ExecuteDataset(transaction, CommandType.StoredProcedure, spName);

            }

        }



        #endregion ExecuteDataSet



        #region ExecuteReader



        /// <summary>

        /// this enum is used to indicate whether the connection was provided by the caller, or created by SqlHelper, so that

        /// we can set the appropriate CommandBehavior when calling ExecuteReader()

        /// </summary>

        private enum SqlConnectionOwnership

        {

            /// <summary>Connection is owned and managed by SqlHelper</summary>

            Internal,

            /// <summary>Connection is owned and managed by the caller</summary>

            External

        }



        /// <summary>

        /// Create and prepare a SqlCommand, and call ExecuteReader with the appropriate CommandBehavior.

        /// </summary>

        /// <remarks>

        /// If we created and opened the connection, we want the connection to be closed when the DataReader is closed.

        /// 

        /// If the caller provided the connection, we want to leave it to them to manage.

        /// </remarks>

        /// <param name="connection">a valid SqlConnection, on which to execute this command</param>

        /// <param name="transaction">a valid SqlTransaction, or 'null'</param>

        /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>

        /// <param name="commandText">the stored procedure name or T-SQL command</param>

        /// <param name="commandParameters">an array of SqlParameters to be associated with the command or 'null' if no parameters are required</param>

        /// <param name="connectionOwnership">indicates whether the connection parameter was provided by the caller, or created by SqlHelper</param>

        /// <returns>SqlDataReader containing the results of the command</returns>

        private static SqlDataReader ExecuteReader(SqlConnection connection, SqlTransaction transaction, CommandType commandType, 

string commandText, SqlParameter[] commandParameters, SqlConnectionOwnership connectionOwnership)

        {

            //create a command and prepare it for execution

            SqlCommand cmd = new SqlCommand();

            PrepareCommand(cmd, connection, transaction, commandType, commandText, commandParameters);



            //create a reader

            SqlDataReader dr;



            // call ExecuteReader with the appropriate CommandBehavior

            if (connectionOwnership == SqlConnectionOwnership.External)

            {

                dr = cmd.ExecuteReader();

            }

            else

            {

                dr = cmd.ExecuteReader(CommandBehavior.CloseConnection);

            }



            // detach the SqlParameters from the command object, so they can be used again.

            cmd.Parameters.Clear();



            return dr;

        }



        /// <summary>

        /// Execute a SqlCommand (that returns a resultset and takes no parameters) against the database specified in 

        /// the connection string. 

        /// </summary>

        /// <remarks>

        /// e.g.:  

        ///  SqlDataReader dr = ExecuteReader(connString, CommandType.StoredProcedure, "GetOrders");

        /// </remarks>

        /// <param name="connectionString">a valid connection string for a SqlConnection</param>

        /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>

        /// <param name="commandText">the stored procedure name or T-SQL command</param>

        /// <returns>a SqlDataReader containing the resultset generated by the command</returns>

        public static SqlDataReader ExecuteReader(string connectionString, CommandType commandType, string commandText)

        {

            //pass through the call providing null for the set of SqlParameters

            return ExecuteReader(connectionString, commandType, commandText, (SqlParameter[])null);

        }



        /// <summary>

        /// Execute a SqlCommand (that returns a resultset) against the database specified in the connection string 

        /// using the provided parameters.

        /// </summary>

        /// <remarks>

        /// e.g.:  

        ///  SqlDataReader dr = ExecuteReader(connString, CommandType.StoredProcedure, "GetOrders", new SqlParameter("@prodid", 24));

        /// </remarks>

        /// <param name="connectionString">a valid connection string for a SqlConnection</param>

        /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>

        /// <param name="commandText">the stored procedure name or T-SQL command</param>

        /// <param name="commandParameters">an array of SqlParamters used to execute the command</param>

        /// <returns>a SqlDataReader containing the resultset generated by the command</returns>

        public static SqlDataReader ExecuteReader(string connectionString, CommandType commandType, string commandText,

 params SqlParameter[] commandParameters)

        {

            //create & open a SqlConnection

            SqlConnection cn = new SqlConnection(connectionString);

            cn.Open();



            try

            {

                //call the private overload that takes an internally owned connection in place of the connection string

                return ExecuteReader(cn, null, commandType, commandText, commandParameters, SqlConnectionOwnership.Internal);

            }

            catch

            {

                //if we fail to return the SqlDatReader, we need to close the connection ourselves

                cn.Close();

                throw;

            }

        }



        /// <summary>

        /// Execute a stored procedure via a SqlCommand (that returns a resultset) against the database specified in 

        /// the connection string using the provided parameter values.  This method will query the database to discover the parameters for the 

        /// stored procedure (the first time each stored procedure is called), and assign the values based on parameter order.

        /// </summary>

        /// <remarks>

        /// This method provides no access to output parameters or the stored procedure's return value parameter.

        /// 

        /// e.g.:  

        ///  SqlDataReader dr = ExecuteReader(connString, "GetOrders", 24, 36);

        /// </remarks>

        /// <param name="connectionString">a valid connection string for a SqlConnection</param>

        /// <param name="spName">the name of the stored procedure</param>

        /// <param name="parameterValues">an array of objects to be assigned as the input values of the stored procedure</param>

        /// <returns>a SqlDataReader containing the resultset generated by the command</returns>

        public static SqlDataReader ExecuteReader(string connectionString, string spName, params object[] parameterValues)

        {

            //if we receive parameter values, we need to figure out where they go

            if ((parameterValues != null) && (parameterValues.Length > 0))

            {

                //pull the parameters for this stored procedure from the parameter cache (or discover them & populate the cache)

                SqlParameter[] commandParameters = SqlParameterClass.GetSpParameterSet(connectionString, spName);



                //assign the provided values to these parameters based on parameter order

                AssignParameterValues(commandParameters, parameterValues);



                //call the overload that takes an array of SqlParameters

                return ExecuteReader(connectionString, CommandType.StoredProcedure, spName, commandParameters);

            }

            //otherwise we can just call the SP without params

            else

            {

                return ExecuteReader(connectionString, CommandType.StoredProcedure, spName);

            }

        }



        /// <summary>

        /// Execute a SqlCommand (that returns a resultset and takes no parameters) against the provided SqlConnection. 

        /// </summary>

        /// <remarks>

        /// e.g.:  

        ///  SqlDataReader dr = ExecuteReader(conn, CommandType.StoredProcedure, "GetOrders");

        /// </remarks>

        /// <param name="connection">a valid SqlConnection</param>

        /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>

        /// <param name="commandText">the stored procedure name or T-SQL command</param>

        /// <returns>a SqlDataReader containing the resultset generated by the command</returns>

        public static SqlDataReader ExecuteReader(SqlConnection connection, CommandType commandType, string commandText)

        {

            //pass through the call providing null for the set of SqlParameters

            return ExecuteReader(connection, commandType, commandText, (SqlParameter[])null);

        }



        /// <summary>

        /// Execute a SqlCommand (that returns a resultset) against the specified SqlConnection 

        /// using the provided parameters.

        /// </summary>

        /// <remarks>

        /// e.g.:  

        ///  SqlDataReader dr = ExecuteReader(conn, CommandType.StoredProcedure, "GetOrders", new SqlParameter("@prodid", 24));

        /// </remarks>

        /// <param name="connection">a valid SqlConnection</param>

        /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>

        /// <param name="commandText">the stored procedure name or T-SQL command</param>

        /// <param name="commandParameters">an array of SqlParamters used to execute the command</param>

        /// <returns>a SqlDataReader containing the resultset generated by the command</returns>

        public static SqlDataReader ExecuteReader(SqlConnection connection, CommandType commandType, string commandText, 

params SqlParameter[] commandParameters)

        {

            //pass through the call to the private overload using a null transaction value and an externally owned connection

            return ExecuteReader(connection, (SqlTransaction)null, commandType, commandText, commandParameters, SqlConnectionOwnership.External);

        }



        /// <summary>

        /// Execute a stored procedure via a SqlCommand (that returns a resultset) against the specified SqlConnection 

        /// using the provided parameter values.  This method will query the database to discover the parameters for the 

        /// stored procedure (the first time each stored procedure is called), and assign the values based on parameter order.

        /// </summary>

        /// <remarks>

        /// This method provides no access to output parameters or the stored procedure's return value parameter.

        /// 

        /// e.g.:  

        ///  SqlDataReader dr = ExecuteReader(conn, "GetOrders", 24, 36);

        /// </remarks>

        /// <param name="connection">a valid SqlConnection</param>

        /// <param name="spName">the name of the stored procedure</param>

        /// <param name="parameterValues">an array of objects to be assigned as the input values of the stored procedure</param>

        /// <returns>a SqlDataReader containing the resultset generated by the command</returns>

        public static SqlDataReader ExecuteReader(SqlConnection connection, string spName, params object[] parameterValues)

        {

            //if we receive parameter values, we need to figure out where they go

            if ((parameterValues != null) && (parameterValues.Length > 0))

            {

                SqlParameter[] commandParameters = SqlParameterClass.GetSpParameterSet(connection.ConnectionString, spName);



                AssignParameterValues(commandParameters, parameterValues);



                return ExecuteReader(connection, CommandType.StoredProcedure, spName, commandParameters);

            }

            //otherwise we can just call the SP without params

            else

            {

                return ExecuteReader(connection, CommandType.StoredProcedure, spName);

            }

        }



        /// <summary>

        /// Execute a SqlCommand (that returns a resultset and takes no parameters) against the provided SqlTransaction. 

        /// </summary>

        /// <remarks>

        /// e.g.:  

        ///  SqlDataReader dr = ExecuteReader(trans, CommandType.StoredProcedure, "GetOrders");

        /// </remarks>

        /// <param name="transaction">a valid SqlTransaction</param>

        /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>

        /// <param name="commandText">the stored procedure name or T-SQL command</param>

        /// <returns>a SqlDataReader containing the resultset generated by the command</returns>

        public static SqlDataReader ExecuteReader(SqlTransaction transaction, CommandType commandType, string commandText)

        {

            //pass through the call providing null for the set of SqlParameters

            return ExecuteReader(transaction, commandType, commandText, (SqlParameter[])null);

        }



        /// <summary>

        /// Execute a SqlCommand (that returns a resultset) against the specified SqlTransaction

        /// using the provided parameters.

        /// </summary>

        /// <remarks>

        /// e.g.:  

        ///   SqlDataReader dr = ExecuteReader(trans, CommandType.StoredProcedure, "GetOrders", new SqlParameter("@prodid", 24));

        /// </remarks>

        /// <param name="transaction">a valid SqlTransaction</param>

        /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>

        /// <param name="commandText">the stored procedure name or T-SQL command</param>

        /// <param name="commandParameters">an array of SqlParamters used to execute the command</param>

        /// <returns>a SqlDataReader containing the resultset generated by the command</returns>

        public static SqlDataReader ExecuteReader(SqlTransaction transaction, CommandType commandType, string commandText,

 params SqlParameter[] commandParameters)

        {

            //pass through to private overload, indicating that the connection is owned by the caller

            return ExecuteReader(transaction.Connection, transaction, commandType, commandText, commandParameters, SqlConnectionOwnership.External);

        }



        /// <summary>

        /// Execute a stored procedure via a SqlCommand (that returns a resultset) against the specified

        /// SqlTransaction using the provided parameter values.  This method will query the database to discover the parameters for the 

        /// stored procedure (the first time each stored procedure is called), and assign the values based on parameter order.

        /// </summary>

        /// <remarks>

        /// This method provides no access to output parameters or the stored procedure's return value parameter.

        /// 

        /// e.g.:  

        ///  SqlDataReader dr = ExecuteReader(trans, "GetOrders", 24, 36);

        /// </remarks>

        /// <param name="transaction">a valid SqlTransaction</param>

        /// <param name="spName">the name of the stored procedure</param>

        /// <param name="parameterValues">an array of objects to be assigned as the input values of the stored procedure</param>

        /// <returns>a SqlDataReader containing the resultset generated by the command</returns>

        public static SqlDataReader ExecuteReader(SqlTransaction transaction, string spName, params object[] parameterValues)

        {

            //if we receive parameter values, we need to figure out where they go

            if ((parameterValues != null) && (parameterValues.Length > 0))

            {

                SqlParameter[] commandParameters = SqlParameterClass.GetSpParameterSet(transaction.Connection.ConnectionString, spName);



                AssignParameterValues(commandParameters, parameterValues);



                return ExecuteReader(transaction, CommandType.StoredProcedure, spName, commandParameters);

            }

            //otherwise we can just call the SP without params

            else

            {

                return ExecuteReader(transaction, CommandType.StoredProcedure, spName);

            }

        }



        #endregion ExecuteReader



        #region ExecuteScalar



        /// <summary>

        /// Execute a SqlCommand (that returns a 1x1 resultset and takes no parameters) against the database specified in 

        /// the connection string. 

        /// </summary>

        /// <remarks>

        /// e.g.:  

        ///  int orderCount = (int)ExecuteScalar(connString, CommandType.StoredProcedure, "GetOrderCount");

        /// </remarks>

        /// <param name="connectionString">a valid connection string for a SqlConnection</param>

        /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>

        /// <param name="commandText">the stored procedure name or T-SQL command</param>

        /// <returns>an object containing the value in the 1x1 resultset generated by the command</returns>

        public static object ExecuteScalar(string connectionString, CommandType commandType, string commandText)

        {

            //pass through the call providing null for the set of SqlParameters

            return ExecuteScalar(connectionString, commandType, commandText, (SqlParameter[])null);

        }



        /// <summary>

        /// Execute a SqlCommand (that returns a 1x1 resultset) against the database specified in the connection string 

        /// using the provided parameters.

        /// </summary>

        /// <remarks>

        /// e.g.:  

        ///  int orderCount = (int)ExecuteScalar(connString, CommandType.StoredProcedure, "GetOrderCount", new SqlParameter("@prodid", 24));

        /// </remarks>

        /// <param name="connectionString">a valid connection string for a SqlConnection</param>

        /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>

        /// <param name="commandText">the stored procedure name or T-SQL command</param>

        /// <param name="commandParameters">an array of SqlParamters used to execute the command</param>

        /// <returns>an object containing the value in the 1x1 resultset generated by the command</returns>

        public static object ExecuteScalar(string connectionString, CommandType commandType, string commandText, 

params SqlParameter[] commandParameters)

        {

            //create & open a SqlConnection, and dispose of it after we are done.

            using (SqlConnection cn = new SqlConnection(connectionString))

            {

                cn.Open();



                //call the overload that takes a connection in place of the connection string

                return ExecuteScalar(cn, commandType, commandText, commandParameters);

            }

        }



        /// <summary>

        /// Execute a stored procedure via a SqlCommand (that returns a 1x1 resultset) against the database specified in 

        /// the connection string using the provided parameter values.  This method will query the database to discover the parameters for the 

        /// stored procedure (the first time each stored procedure is called), and assign the values based on parameter order.

        /// </summary>

        /// <remarks>

        /// This method provides no access to output parameters or the stored procedure's return value parameter.

        /// 

        /// e.g.:  

        ///  int orderCount = (int)ExecuteScalar(connString, "GetOrderCount", 24, 36);

        /// </remarks>

        /// <param name="connectionString">a valid connection string for a SqlConnection</param>

        /// <param name="spName">the name of the stored procedure</param>

        /// <param name="parameterValues">an array of objects to be assigned as the input values of the stored procedure</param>

        /// <returns>an object containing the value in the 1x1 resultset generated by the command</returns>

        public static object ExecuteScalar(string connectionString, string spName, params object[] parameterValues)

        {

            //if we receive parameter values, we need to figure out where they go

            if ((parameterValues != null) && (parameterValues.Length > 0))

            {

                //pull the parameters for this stored procedure from the parameter cache (or discover them & populate the cache)

                SqlParameter[] commandParameters = SqlParameterClass.GetSpParameterSet(connectionString, spName);



                //assign the provided values to these parameters based on parameter order

                AssignParameterValues(commandParameters, parameterValues);



                //call the overload that takes an array of SqlParameters

                return ExecuteScalar(connectionString, CommandType.StoredProcedure, spName, commandParameters);

            }

            //otherwise we can just call the SP without params

            else

            {

                return ExecuteScalar(connectionString, CommandType.StoredProcedure, spName);

            }

        }



        /// <summary>

        /// Execute a SqlCommand (that returns a 1x1 resultset and takes no parameters) against the provided SqlConnection. 

        /// </summary>

        /// <remarks>

        /// e.g.:  

        ///  int orderCount = (int)ExecuteScalar(conn, CommandType.StoredProcedure, "GetOrderCount");

        /// </remarks>

        /// <param name="connection">a valid SqlConnection</param>

        /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>

        /// <param name="commandText">the stored procedure name or T-SQL command</param>

        /// <returns>an object containing the value in the 1x1 resultset generated by the command</returns>

        public static object ExecuteScalar(SqlConnection connection, CommandType commandType, string commandText)

        {

            //pass through the call providing null for the set of SqlParameters

            return ExecuteScalar(connection, commandType, commandText, (SqlParameter[])null);

        }



        /// <summary>

        /// Execute a SqlCommand (that returns a 1x1 resultset) against the specified SqlConnection 

        /// using the provided parameters.

        /// </summary>

        /// <remarks>

        /// e.g.:  

        ///  int orderCount = (int)ExecuteScalar(conn, CommandType.StoredProcedure, "GetOrderCount", new SqlParameter("@prodid", 24));

        /// </remarks>

        /// <param name="connection">a valid SqlConnection</param>

        /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>

        /// <param name="commandText">the stored procedure name or T-SQL command</param>

        /// <param name="commandParameters">an array of SqlParamters used to execute the command</param>

        /// <returns>an object containing the value in the 1x1 resultset generated by the command</returns>

        public static object ExecuteScalar(SqlConnection connection, CommandType commandType, string commandText, 

params SqlParameter[] commandParameters)

        {

            //create a command and prepare it for execution

            SqlCommand cmd = new SqlCommand();

            PrepareCommand(cmd, connection, (SqlTransaction)null, commandType, commandText, commandParameters);



            //execute the command & return the results

            object retval = cmd.ExecuteScalar();



            // detach the SqlParameters from the command object, so they can be used again.

            cmd.Parameters.Clear();

            return retval;



        }



        /// <summary>

        /// Execute a stored procedure via a SqlCommand (that returns a 1x1 resultset) against the specified SqlConnection 

        /// using the provided parameter values.  This method will query the database to discover the parameters for the 

        /// stored procedure (the first time each stored procedure is called), and assign the values based on parameter order.

        /// </summary>

        /// <remarks>

        /// This method provides no access to output parameters or the stored procedure's return value parameter.

        /// 

        /// e.g.:  

        ///  int orderCount = (int)ExecuteScalar(conn, "GetOrderCount", 24, 36);

        /// </remarks>

        /// <param name="connection">a valid SqlConnection</param>

        /// <param name="spName">the name of the stored procedure</param>

        /// <param name="parameterValues">an array of objects to be assigned as the input values of the stored procedure</param>

        /// <returns>an object containing the value in the 1x1 resultset generated by the command</returns>

        public static object ExecuteScalar(SqlConnection connection, string spName, params object[] parameterValues)

        {

            //if we receive parameter values, we need to figure out where they go

            if ((parameterValues != null) && (parameterValues.Length > 0))

            {

                //pull the parameters for this stored procedure from the parameter cache (or discover them & populate the cache)

                SqlParameter[] commandParameters = SqlParameterClass.GetSpParameterSet(connection.ConnectionString, spName);



                //assign the provided values to these parameters based on parameter order

                AssignParameterValues(commandParameters, parameterValues);



                //call the overload that takes an array of SqlParameters

                return ExecuteScalar(connection, CommandType.StoredProcedure, spName, commandParameters);

            }

            //otherwise we can just call the SP without params

            else

            {

                return ExecuteScalar(connection, CommandType.StoredProcedure, spName);

            }

        }



        /// <summary>

        /// Execute a SqlCommand (that returns a 1x1 resultset and takes no parameters) against the provided SqlTransaction. 

        /// </summary>

        /// <remarks>

        /// e.g.:  

        ///  int orderCount = (int)ExecuteScalar(trans, CommandType.StoredProcedure, "GetOrderCount");

        /// </remarks>

        /// <param name="transaction">a valid SqlTransaction</param>

        /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>

        /// <param name="commandText">the stored procedure name or T-SQL command</param>

        /// <returns>an object containing the value in the 1x1 resultset generated by the command</returns>

        public static object ExecuteScalar(SqlTransaction transaction, CommandType commandType, string commandText)

        {

            //pass through the call providing null for the set of SqlParameters

            return ExecuteScalar(transaction, commandType, commandText, (SqlParameter[])null);

        }



        /// <summary>

        /// Execute a SqlCommand (that returns a 1x1 resultset) against the specified SqlTransaction

        /// using the provided parameters.

        /// </summary>

        /// <remarks>

        /// e.g.:  

        ///  int orderCount = (int)ExecuteScalar(trans, CommandType.StoredProcedure, "GetOrderCount", new SqlParameter("@prodid", 24));

        /// </remarks>

        /// <param name="transaction">a valid SqlTransaction</param>

        /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>

        /// <param name="commandText">the stored procedure name or T-SQL command</param>

        /// <param name="commandParameters">an array of SqlParamters used to execute the command</param>

        /// <returns>an object containing the value in the 1x1 resultset generated by the command</returns>

        public static object ExecuteScalar(SqlTransaction transaction, CommandType commandType, string commandText, 

params SqlParameter[] commandParameters)

        {

            //create a command and prepare it for execution

            SqlCommand cmd = new SqlCommand();

            PrepareCommand(cmd, transaction.Connection, transaction, commandType, commandText, commandParameters);



            //execute the command & return the results

            object retval = cmd.ExecuteScalar();



            // detach the SqlParameters from the command object, so they can be used again.

            cmd.Parameters.Clear();

            return retval;

        }



        /// <summary>

        /// Execute a stored procedure via a SqlCommand (that returns a 1x1 resultset) against the specified

        /// SqlTransaction using the provided parameter values.  This method will query the database to discover the parameters for the 

        /// stored procedure (the first time each stored procedure is called), and assign the values based on parameter order.

        /// </summary>

        /// <remarks>

        /// This method provides no access to output parameters or the stored procedure's return value parameter.

        /// 

        /// e.g.:  

        ///  int orderCount = (int)ExecuteScalar(trans, "GetOrderCount", 24, 36);

        /// </remarks>

        /// <param name="transaction">a valid SqlTransaction</param>

        /// <param name="spName">the name of the stored procedure</param>

        /// <param name="parameterValues">an array of objects to be assigned as the input values of the stored procedure</param>

        /// <returns>an object containing the value in the 1x1 resultset generated by the command</returns>

        public static object ExecuteScalar(SqlTransaction transaction, string spName, params object[] parameterValues)

        {

            //if we receive parameter values, we need to figure out where they go

            if ((parameterValues != null) && (parameterValues.Length > 0))

            {

                //pull the parameters for this stored procedure from the parameter cache (or discover them & populate the cache)

                SqlParameter[] commandParameters = SqlParameterClass.GetSpParameterSet(transaction.Connection.ConnectionString, spName);



                //assign the provided values to these parameters based on parameter order

                AssignParameterValues(commandParameters, parameterValues);



                //call the overload that takes an array of SqlParameters

                return ExecuteScalar(transaction, CommandType.StoredProcedure, spName, commandParameters);

            }

            //otherwise we can just call the SP without params

            else

            {

                return ExecuteScalar(transaction, CommandType.StoredProcedure, spName);

            }

        }



        #endregion ExecuteScalar



        #region ExecuteXmlReader



        /// <summary>

        /// Execute a SqlCommand (that returns a resultset and takes no parameters) against the provided SqlConnection. 

        /// </summary>

        /// <remarks>

        /// e.g.:  

        ///  XmlReader r = ExecuteXmlReader(conn, CommandType.StoredProcedure, "GetOrders");

        /// </remarks>

        /// <param name="connection">a valid SqlConnection</param>

        /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>

        /// <param name="commandText">the stored procedure name or T-SQL command using "FOR XML AUTO"</param>

        /// <returns>an XmlReader containing the resultset generated by the command</returns>

        public static XmlReader ExecuteXmlReader(SqlConnection connection, CommandType commandType, string commandText)

        {

            //pass through the call providing null for the set of SqlParameters

            return ExecuteXmlReader(connection, commandType, commandText, (SqlParameter[])null);

        }



        /// <summary>

        /// Execute a SqlCommand (that returns a resultset) against the specified SqlConnection 

        /// using the provided parameters.

        /// </summary>

        /// <remarks>

        /// e.g.:  

        ///  XmlReader r = ExecuteXmlReader(conn, CommandType.StoredProcedure, "GetOrders", new SqlParameter("@prodid", 24));

        /// </remarks>

        /// <param name="connection">a valid SqlConnection</param>

        /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>

        /// <param name="commandText">the stored procedure name or T-SQL command using "FOR XML AUTO"</param>

        /// <param name="commandParameters">an array of SqlParamters used to execute the command</param>

        /// <returns>an XmlReader containing the resultset generated by the command</returns>

        public static XmlReader ExecuteXmlReader(SqlConnection connection, CommandType commandType, string commandText,

params SqlParameter[] commandParameters)

        {

            //create a command and prepare it for execution

            SqlCommand cmd = new SqlCommand();

            PrepareCommand(cmd, connection, (SqlTransaction)null, commandType, commandText, commandParameters);



            //create the DataAdapter & DataSet

            XmlReader retval = cmd.ExecuteXmlReader();



            // detach the SqlParameters from the command object, so they can be used again.

            cmd.Parameters.Clear();

            return retval;



        }



        /// <summary>

        /// Execute a stored procedure via a SqlCommand (that returns a resultset) against the specified SqlConnection 

        /// using the provided parameter values.  This method will query the database to discover the parameters for the 

        /// stored procedure (the first time each stored procedure is called), and assign the values based on parameter order.

        /// </summary>

        /// <remarks>

        /// This method provides no access to output parameters or the stored procedure's return value parameter.

        /// 

        /// e.g.:  

        ///  XmlReader r = ExecuteXmlReader(conn, "GetOrders", 24, 36);

        /// </remarks>

        /// <param name="connection">a valid SqlConnection</param>

        /// <param name="spName">the name of the stored procedure using "FOR XML AUTO"</param>

        /// <param name="parameterValues">an array of objects to be assigned as the input values of the stored procedure</param>

        /// <returns>an XmlReader containing the resultset generated by the command</returns>

        public static XmlReader ExecuteXmlReader(SqlConnection connection, string spName, params object[] parameterValues)

        {

            //if we receive parameter values, we need to figure out where they go

            if ((parameterValues != null) && (parameterValues.Length > 0))

            {

                //pull the parameters for this stored procedure from the parameter cache (or discover them & populate the cache)

                SqlParameter[] commandParameters = SqlParameterClass.GetSpParameterSet(connection.ConnectionString, spName);



                //assign the provided values to these parameters based on parameter order

                AssignParameterValues(commandParameters, parameterValues);



                //call the overload that takes an array of SqlParameters

                return ExecuteXmlReader(connection, CommandType.StoredProcedure, spName, commandParameters);

            }

            //otherwise we can just call the SP without params

            else

            {

                return ExecuteXmlReader(connection, CommandType.StoredProcedure, spName);

            }

        }



        /// <summary>

        /// Execute a SqlCommand (that returns a resultset and takes no parameters) against the provided SqlTransaction. 

        /// </summary>

        /// <remarks>

        /// e.g.:  

        ///  XmlReader r = ExecuteXmlReader(trans, CommandType.StoredProcedure, "GetOrders");

        /// </remarks>

        /// <param name="transaction">a valid SqlTransaction</param>

        /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>

        /// <param name="commandText">the stored procedure name or T-SQL command using "FOR XML AUTO"</param>

        /// <returns>an XmlReader containing the resultset generated by the command</returns>

        public static XmlReader ExecuteXmlReader(SqlTransaction transaction, CommandType commandType, string commandText)

        {

            //pass through the call providing null for the set of SqlParameters

            return ExecuteXmlReader(transaction, commandType, commandText, (SqlParameter[])null);

        }



        /// <summary>

        /// Execute a SqlCommand (that returns a resultset) against the specified SqlTransaction

        /// using the provided parameters.

        /// </summary>

        /// <remarks>

        /// e.g.:  

        ///  XmlReader r = ExecuteXmlReader(trans, CommandType.StoredProcedure, "GetOrders", new SqlParameter("@prodid", 24));

        /// </remarks>

        /// <param name="transaction">a valid SqlTransaction</param>

        /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>

        /// <param name="commandText">the stored procedure name or T-SQL command using "FOR XML AUTO"</param>

        /// <param name="commandParameters">an array of SqlParamters used to execute the command</param>

        /// <returns>an XmlReader containing the resultset generated by the command</returns>

        public static XmlReader ExecuteXmlReader(SqlTransaction transaction, CommandType commandType, string commandText, 

params SqlParameter[] commandParameters)

        {

            //create a command and prepare it for execution

            SqlCommand cmd = new SqlCommand();

            PrepareCommand(cmd, transaction.Connection, transaction, commandType, commandText, commandParameters);



            //create the DataAdapter & DataSet

            XmlReader retval = cmd.ExecuteXmlReader();



            // detach the SqlParameters from the command object, so they can be used again.

            cmd.Parameters.Clear();

            return retval;

        }



        /// <summary>

        /// Execute a stored procedure via a SqlCommand (that returns a resultset) against the specified 

        /// SqlTransaction using the provided parameter values.  This method will query the database to discover the parameters for the 

        /// stored procedure (the first time each stored procedure is called), and assign the values based on parameter order.

        /// </summary>

        /// <remarks>

        /// This method provides no access to output parameters or the stored procedure's return value parameter.

        /// 

        /// e.g.:  

        ///  XmlReader r = ExecuteXmlReader(trans, "GetOrders", 24, 36);

        /// </remarks>

        /// <param name="transaction">a valid SqlTransaction</param>

        /// <param name="spName">the name of the stored procedure</param>

        /// <param name="parameterValues">an array of objects to be assigned as the input values of the stored procedure</param>

        /// <returns>a dataset containing the resultset generated by the command</returns>

        public static XmlReader ExecuteXmlReader(SqlTransaction transaction, string spName, params object[] parameterValues)

        {

            //if we receive parameter values, we need to figure out where they go

            if ((parameterValues != null) && (parameterValues.Length > 0))

            {

                //pull the parameters for this stored procedure from the parameter cache (or discover them & populate the cache)

                SqlParameter[] commandParameters = SqlParameterClass.GetSpParameterSet(transaction.Connection.ConnectionString, spName);



                //assign the provided values to these parameters based on parameter order

                AssignParameterValues(commandParameters, parameterValues);



                //call the overload that takes an array of SqlParameters

                return ExecuteXmlReader(transaction, CommandType.StoredProcedure, spName, commandParameters);

            }

            //otherwise we can just call the SP without params

            else

            {

                return ExecuteXmlReader(transaction, CommandType.StoredProcedure, spName);

            }

        }





        #endregion ExecuteXmlReader





        public static int OleDbExecuteNonQuery(string connectionString, string commandText)

        {

            //create & open a SqlConnection, and dispose of it after we are done.

            using (OleDbConnection cn = new OleDbConnection(connectionString))

            {

                try

                {

                    cn.Open();

                }

                catch (Exception)

                {



                    return -1;

                }

                OleDbCommand myCommand = new OleDbCommand(commandText, cn);

                int ret=myCommand.ExecuteNonQuery();

                cn.Close();

                return ret;

                //call the overload that takes a connection in place of the connection string



            }

        }

        public static DataSet OleDbExecuteDataset(string connectionString, string commandText)

        {

            //create & open a SqlConnection, and dispose of it after we are done.

            using (OleDbConnection cn = new OleDbConnection(connectionString))

            {

                try

                {

                    cn.Open();

                    OleDbCommand myCommand = new OleDbCommand(commandText, cn);

                    OleDbDataAdapter da = new OleDbDataAdapter(myCommand);

                    DataSet ds = new DataSet();



                    //fill the DataSet using default values for DataTable names, etc.

                    da.Fill(ds);



                    // detach the SqlParameters from the command object, so they can be used again.

                    myCommand.Parameters.Clear();



                    //return the dataset

                    cn.Close();

                    return ds;



                    //call the overload that takes a connection in place of the connection string

                }

                catch (Exception)

                {

                    cn.Close();

                    return null;

                }

            }

        }

    }
  public sealed class SqlParameterClass

    {

        #region private methods, variables, and constructors



        //Since this class provides only static methods, make the default constructor private to prevent 

        //instances from being created with "new SqlServerClass()".

        private SqlParameterClass() { }



        private static Hashtable paramCache = Hashtable.Synchronized(new Hashtable());



        /// <summary>

        /// resolve at run time the appropriate set of SqlParameters for a stored procedure

        /// </summary>

        /// <param name="connectionString">a valid connection string for a SqlConnection</param>

        /// <param name="spName">the name of the stored procedure</param>

        /// <param name="includeReturnValueParameter">whether or not to include their return value parameter</param>

        /// <returns></returns>

        private static SqlParameter[] DiscoverSpParameterSet(string connectionString, string spName, bool includeReturnValueParameter)

        {

            using (SqlConnection cn = new SqlConnection(connectionString))

            using (SqlCommand cmd = new SqlCommand(spName, cn))

            {

                cn.Open();

                cmd.CommandType = CommandType.StoredProcedure;



                SqlCommandBuilder.DeriveParameters(cmd);



                if (!includeReturnValueParameter)

                {

                    cmd.Parameters.RemoveAt(0);

                }



                SqlParameter[] discoveredParameters = new SqlParameter[cmd.Parameters.Count]; ;



                cmd.Parameters.CopyTo(discoveredParameters, 0);



                return discoveredParameters;

            }

        }



        //deep copy of cached SqlParameter array

        private static SqlParameter[] CloneParameters(SqlParameter[] originalParameters)

        {

            SqlParameter[] clonedParameters = new SqlParameter[originalParameters.Length];



            for (int i = 0, j = originalParameters.Length; i < j; i++)

            {

                clonedParameters[i] = (SqlParameter)((ICloneable)originalParameters[i]).Clone();

            }



            return clonedParameters;

        }



        #endregion private methods, variables, and constructors



        #region caching functions



        /// <summary>

        /// add parameter array to the cache

        /// </summary>

        /// <param name="connectionString">a valid connection string for a SqlConnection</param>

        /// <param name="commandText">the stored procedure name or T-SQL command</param>

        /// <param name="commandParameters">an array of SqlParamters to be cached</param>

        public static void CacheParameterSet(string connectionString, string commandText, params SqlParameter[] commandParameters)

        {

            string hashKey = connectionString + ":" + commandText;



            paramCache[hashKey] = commandParameters;

        }



        /// <summary>

        /// retrieve a parameter array from the cache

        /// </summary>

        /// <param name="connectionString">a valid connection string for a SqlConnection</param>

        /// <param name="commandText">the stored procedure name or T-SQL command</param>

        /// <returns>an array of SqlParamters</returns>

        public static SqlParameter[] GetCachedParameterSet(string connectionString, string commandText)

        {

            string hashKey = connectionString + ":" + commandText;



            SqlParameter[] cachedParameters = (SqlParameter[])paramCache[hashKey];



            if (cachedParameters == null)

            {

                return null;

            }

            else

            {

                return CloneParameters(cachedParameters);

            }

        }



        #endregion caching functions



        #region Parameter Discovery Functions



        /// <summary>

        /// Retrieves the set of SqlParameters appropriate for the stored procedure

        /// </summary>

        /// <remarks>

        /// This method will query the database for this information, and then store it in a cache for future requests.

        /// </remarks>

        /// <param name="connectionString">a valid connection string for a SqlConnection</param>

        /// <param name="spName">the name of the stored procedure</param>

        /// <returns>an array of SqlParameters</returns>

        public static SqlParameter[] GetSpParameterSet(string connectionString, string spName)

        {

            return GetSpParameterSet(connectionString, spName, false);

        }



        /// <summary>

        /// Retrieves the set of SqlParameters appropriate for the stored procedure

        /// </summary>

        /// <remarks>

        /// This method will query the database for this information, and then store it in a cache for future requests.

        /// </remarks>

        /// <param name="connectionString">a valid connection string for a SqlConnection</param>

        /// <param name="spName">the name of the stored procedure</param>

        /// <param name="includeReturnValueParameter">a bool value indicating whether the return value parameter should be included in the results</param>

        /// <returns>an array of SqlParameters</returns>

        public static SqlParameter[] GetSpParameterSet(string connectionString, string spName, bool includeReturnValueParameter)

        {

            string hashKey = connectionString + ":" + spName + (includeReturnValueParameter ? ":include ReturnValue Parameter" : "");



            SqlParameter[] cachedParameters;



            cachedParameters = (SqlParameter[])paramCache[hashKey];



            if (cachedParameters == null)

            {

                cachedParameters = (SqlParameter[])(paramCache[hashKey] = DiscoverSpParameterSet(connectionString, spName, includeReturnValueParameter));

            }



            return CloneParameters(cachedParameters);

        }



        #endregion Parameter Discovery Functions

    }



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