数据库连接的多种方式(一)

public class Helper



    {



        private static string cons = "server=.;uid=sa;pwd=;database=pubs";



        //查询



        public static DataTable ExecuteDataQuery(string sql)



        {



            using (SqlConnection con = new SqlConnection(cons))



            {



                con.Open();



                DataTable tbl = new DataTable();



                SqlDataAdapter adap = new SqlDataAdapter(sql, con);



                adap.Fill(tbl);



                return tbl;



            }





        }



        public static SqlDataReader ExecuteDataQuery(string sql)



        {



            SqlConnection con = new SqlConnection(cons);



            SqlCommand cmd = new SqlCommand(sql, con);



            con.Open();



            return cmd.ExecuteReader(CommandBehavior.CloseConnection);





        }



        //增删改



        public static void ExecuteNonQuery(string sql)



        {



            using (SqlConnection con = new SqlConnection(cons))



            {



                con.Open();



                SqlCommand cmd = new SqlCommand(sql, con);



                cmd.ExecuteNonQuery();



            }



        }



    }



------------------------------------------------------------------------------------------------------------------------------



using System;

using System.Collections;

using System.Collections.Specialized;

using System.Data;

using System.Data.SqlClient;

using System.Configuration;





/// <summary>

/// Copyright (C) 2004-2008 LiTianPing 

/// 数据访问基础类(基于SQLServer)

/// 用户可以修改满足自己项目的需要。

/// </summary>

public abstract class DbHelperSQL

{

    protected static string connectionString = CFunc.ConnectionString;

    public static SqlConnection conn = null;



    public static void connColse()

    {

        if (conn.State == ConnectionState.Open)

        {

            conn.Close();

        }

    }

    #region 执行简单SQL语句



    /// <summary>

    /// 执行SQL语句，返回影响的记录数

    /// </summary>

    /// <param name="SQLString">SQL语句</param>

    /// <returns>影响的记录数</returns>

    public static int ExecuteSql(string SQLString)

    {

        conn = new SqlConnection(connectionString);



        using (SqlCommand cmd = new SqlCommand(SQLString, conn))

        {

            try

            {

                conn.Open();

                int rows = cmd.ExecuteNonQuery();

                return rows;

            }

            catch (System.Data.SqlClient.SqlException E)

            {

                throw new Exception(E.Message);

            }

            finally

            {

                cmd.Dispose();

                conn.Close();

            }

        }



    }



    /// <summary>

    /// 执行多条SQL语句，实现数据库事务。

    /// </summary>

    /// <param name="SQLStringList">多条SQL语句</param>  

    public static void ExecuteSqlTran(ArrayList SQLStringList)

    {

        conn = new SqlConnection(connectionString);



        conn.Open();

        SqlCommand cmd = new SqlCommand();

        cmd.Connection = conn;

        SqlTransaction tx = conn.BeginTransaction();

        cmd.Transaction = tx;

        try

        {

            for (int n = 0; n < SQLStringList.Count; n++)

            {

                string strsql = SQLStringList[n].ToString();

                if (strsql.Trim().Length > 1)

                {

                    cmd.CommandText = strsql;

                    cmd.ExecuteNonQuery();

                }

            }

            tx.Commit();

        }

        catch (System.Data.SqlClient.SqlException E)

        {

            tx.Rollback();

            throw new Exception(E.Message);

        }

        finally

        {

            cmd.Dispose();

            conn.Close();

        }



    }

    /// <summary>

    /// 执行带一个存储过程参数的的SQL语句。

    /// </summary>

    /// <param name="SQLString">SQL语句</param>

    /// <param name="content">参数内容,比如一个字段是格式复杂的文章，有特



殊符号，可以通过这个方式添加</param>

    /// <returns>影响的记录数</returns>

    public static int ExecuteSql(string SQLString, string content)

    {

        conn = new SqlConnection(connectionString);

        SqlCommand cmd = new SqlCommand(SQLString, conn);

        System.Data.SqlClient.SqlParameter myParameter = new



System.Data.SqlClient.SqlParameter("@content", SqlDbType.NText);

        myParameter.Value = content;

        cmd.Parameters.Add(myParameter);

        try

        {

            conn.Open();

            int rows = cmd.ExecuteNonQuery();

            return rows;

        }

        catch (System.Data.SqlClient.SqlException E)

        {

            throw new Exception(E.Message);

        }

        finally

        {

            cmd.Dispose();

            conn.Close();

        }

    }

    /// <summary>

    /// 向数据库里插入图像格式的字段(和上面情况类似的另一种实例)

    /// </summary>

    /// <param name="strSQL">SQL语句</param>

    /// <param name="fs">图像字节,数据库的字段类型为image的情况</param>

    /// <returns>影响的记录数</returns>

    public static int ExecuteSqlInsertImg(string strSQL, byte[] fs)

    {

        conn = new SqlConnection(connectionString);

        SqlCommand cmd = new SqlCommand(strSQL, conn);

        System.Data.SqlClient.SqlParameter myParameter = new



System.Data.SqlClient.SqlParameter("@fs", SqlDbType.Image);

        myParameter.Value = fs;

        cmd.Parameters.Add(myParameter);

        try

        {

            conn.Open();

            int rows = cmd.ExecuteNonQuery();

            return rows;

        }

        catch (System.Data.SqlClient.SqlException E)

        {

            throw new Exception(E.Message);

        }

        finally

        {

            cmd.Dispose();

            conn.Close();

        }

    }



    /// <summary>

    /// 执行一条计算查询结果语句，返回查询结果（object）。

    /// </summary>

    /// <param name="SQLString">计算查询结果语句</param>

    /// <returns>查询结果（object）</returns>

    public static object GetSingle(string SQLString)

    {

        conn = new SqlConnection(connectionString);



        using (SqlCommand cmd = new SqlCommand(SQLString, conn))

        {

            try

            {

                conn.Open();

                object obj = cmd.ExecuteScalar();

                if ((Object.Equals(obj, null)) || (Object.Equals(obj,



System.DBNull.Value)))

                {

                    return null;

                }

                else

                {

                    return obj;

                }

            }

            catch (System.Data.SqlClient.SqlException e)

            {

                conn.Close();

                throw new Exception(e.Message);

            }

            finally

            {

                cmd.Dispose();

                conn.Close();

            }

        }

    }

    /// <summary>

    /// 执行查询语句，返回SqlDataReader

    /// </summary>

    /// <param name="strSQL">查询语句</param>

    /// <returns>SqlDataReader</returns>

    public static SqlDataReader ExecuteReader(string strSQL)

    {//使用完后请关闭conn

        conn = new SqlConnection(connectionString);

        SqlCommand cmd = new SqlCommand(strSQL, conn);

        try

        {

            conn.Open();

            SqlDataReader myReader = cmd.ExecuteReader();

            return myReader;

        }

        catch (System.Data.SqlClient.SqlException e)

        {

            throw new Exception(e.Message);

        }

    }