下面介绍两种执行SQL命令的方法，并作出相应地总结，第一种介绍一种常规用法，下面进行做简要地分析，首先我们需要执行打开数据库操作首先创建一个MySqlConnection对象，在其构造函数中传入一个连接字符串，然后执行Open操作打开数据库，在正确打开数据库之后我们才能进行相关的动作，在ExecuteSQL这个函数中，
我们执行MySqlCommand myCmd = new MySqlCommand(CmdString, conn)，从而创建MySqlCommand对象，其中传入的两个参数分别为sql命令和第一步建立的MySqlConnection对象，然后执行int Cmd = myCmd.ExecuteNonQuery()这一句执行相应的命令，并返回受影响的行数，最后我们需要关闭数据库连接，并释放非托管资源，从而完成整个数据库操作的过程;这个是比较常规的一种做法，也是我们使用比较多的一种形式。
public class DataBaseMySqlHelper
{
string connstr;
MySqlConnection conn;
//Server=xxxxxxx;Database=xxxxxxx;Uid=xxxxxxx;Pwd=xxxxxxx;CharSet=gbk;
//Server=xxx.xx.xxx.xx;Database=MSUP;Uid=dvision;Pwd=dvision;Port=xxxx;allow zero datetime = true;
MainWindow _MainWindow;
public DataBaseMySqlHelper(MainWindow mainWindow)
{
_MainWindow = mainWindow;
connstr = _MainWindow._ConfigInfo.MySqlConnectionStrings;
}
public DataBaseMySqlHelper(MainWindow mainWindow, string connectionString)
{
_MainWindow = mainWindow;
connstr = connectionString;
}
///
/// 打开数据库连接
///
void Open()
{
try
{
conn = new MySqlConnection(connstr);
conn.Open();
}
catch (Exception ex)
{
System.Windows.Forms.MessageBox.Show(ex.Message);
}
}
///
/// 关闭数据库连接
///
void Close()
{
conn.Close();
}
///
/// 返回影响数据库的行数
///
///
///
/// 返回数据表
///
///
///
第二种方式，这里也贴出关键代码并做简要的分析：这里的关键是MySqlParameter[]数组的使用，我们在执行SQL语句的时候 DbHelperMySQL.ExecuteSql(strSql.ToString(),parameters);这里的parameters就是MySqlParameter[]数组，里面存储的是每个字段的数据，我们将在下面的代码中展示parameters的内容，
////// 增加一条数据 /// public void Add(Maticsoft.Model.cameradetail model) { StringBuilder strSql=new StringBuilder(); strSql.Append("insert into cameradetail_gis("); strSql.Append("EncodeDeviceUsername,MatrixIP,EncodeDevicePassword,id,Name,DisplayName,Location,Longitude,Latitude,CameraActive,ServerID,ForwardSvrIP,ForwardSvrPort,EncodeDeviceIP,EncodeDevicePort,CameraType,CameraModel,DeviceChannel,MatrixPort,MatrixChannelNum,VideoStoreServerIP,VideoStoreServerPort,VideoStoreServerUserID,VideoStoreServerPassword,EncodeDeviceModelNum,EncodeDeviceModelName,CameraInstallAddress,CameraStatus)"); strSql.Append(" values ("); strSql.Append("@EncodeDeviceUsername,@MatrixIP,@EncodeDevicePassword,@id,@Name,@DisplayName,@Location,@Longitude,@Latitude,@CameraActive,@ServerID,@ForwardSvrIP,@ForwardSvrPort,@EncodeDeviceIP,@EncodeDevicePort,@CameraType,@CameraModel,@DeviceChannel,@MatrixPort,@MatrixChannelNum,@VideoStoreServerIP,@VideoStoreServerPort,@VideoStoreServerUserID,@VideoStoreServerPassword,@EncodeDeviceModelNum,@EncodeDeviceModelName,@CameraInstallAddress,@CameraStatus)"); MySqlParameter[] parameters = { new MySqlParameter("@EncodeDeviceUsername", MySqlDbType.VarChar,64), new MySqlParameter("@MatrixIP", MySqlDbType.VarChar,16), new MySqlParameter("@EncodeDevicePassword", MySqlDbType.VarChar,64), new MySqlParameter("@id", MySqlDbType.VarChar,14), new MySqlParameter("@Name", MySqlDbType.VarChar,100), new MySqlParameter("@DisplayName", MySqlDbType.VarChar,100), new MySqlParameter("@Location", MySqlDbType.VarChar,250), new MySqlParameter("@Longitude", MySqlDbType.VarChar,16), new MySqlParameter("@Latitude", MySqlDbType.VarChar,16), new MySqlParameter("@CameraActive", MySqlDbType.Int32,11), new MySqlParameter("@ServerID", MySqlDbType.VarChar,16), new MySqlParameter("@ForwardSvrIP", MySqlDbType.VarChar,16), new MySqlParameter("@ForwardSvrPort", MySqlDbType.VarChar,16), new MySqlParameter("@EncodeDeviceIP", MySqlDbType.VarChar,16), new MySqlParameter("@EncodeDevicePort", MySqlDbType.VarChar,6), new MySqlParameter("@CameraType", MySqlDbType.VarChar,6), new MySqlParameter("@CameraModel", MySqlDbType.VarChar,6), new MySqlParameter("@DeviceChannel", MySqlDbType.VarChar,12), new MySqlParameter("@MatrixPort", MySqlDbType.VarChar,6), new MySqlParameter("@MatrixChannelNum", MySqlDbType.VarChar,14), new MySqlParameter("@VideoStoreServerIP", MySqlDbType.VarChar,16), new MySqlParameter("@VideoStoreServerPort", MySqlDbType.VarChar,6), new MySqlParameter("@VideoStoreServerUserID", MySqlDbType.VarChar,50), new MySqlParameter("@VideoStoreServerPassword", MySqlDbType.VarChar,20), new MySqlParameter("@EncodeDeviceModelNum", MySqlDbType.VarChar,6), new MySqlParameter("@EncodeDeviceModelName", MySqlDbType.VarChar,50), new MySqlParameter("@CameraInstallAddress", MySqlDbType.VarChar,250), new MySqlParameter("@CameraStatus", MySqlDbType.Int32,11)}; parameters[0].Value = model.EncodeDeviceUsername; parameters[1].Value = model.MatrixIP; parameters[2].Value = model.EncodeDevicePassword; parameters[3].Value = model.id; parameters[4].Value = model.Name; parameters[5].Value = model.DisplayName; parameters[6].Value = model.Location; parameters[7].Value = model.Longitude; parameters[8].Value = model.Latitude; parameters[9].Value = model.CameraActive; parameters[10].Value = model.ServerID; parameters[11].Value = model.ForwardSvrIP; parameters[12].Value = model.ForwardSvrPort; parameters[13].Value = model.EncodeDeviceIP; parameters[14].Value = model.EncodeDevicePort; parameters[15].Value = model.CameraType; parameters[16].Value = model.CameraModel; parameters[17].Value = model.DeviceChannel; parameters[18].Value = model.MatrixPort; parameters[19].Value = model.MatrixChannelNum; parameters[20].Value = model.VideoStoreServerIP; parameters[21].Value = model.VideoStoreServerPort; parameters[22].Value = model.VideoStoreServerUserID; parameters[23].Value = model.VideoStoreServerPassword; parameters[24].Value = model.EncodeDeviceModelNum; parameters[25].Value = model.EncodeDeviceModelName; parameters[26].Value = model.CameraInstallAddress; parameters[27].Value = model.CameraStatus; DbHelperMySQL.ExecuteSql(strSql.ToString(),parameters); }
这里我们重点来关注DbHelperMySQL.ExecuteSql(strSql.ToString(),parameters)这个函数，函数的源码如下：
这里面有一个重要的函数PrepareCommand(cmd, connection, null, SQLString, cmdParms)，我们这里也贴出相应地源码，并做简要的分析：
这个函数首先是打开数据库连接，这里面最重要就是讲cmdParms里面的参数一个个添加到cmd.Parameters中，然后执行 int rows = cmd.ExecuteNonQuery();命令来执行相应的操作，这是一种决然不同的思路，我们在使用的时候可以考虑这两种方式来进行数据库的插入操作！
private static void PrepareCommand(MySqlCommand cmd, MySqlConnection conn, MySqlTransaction trans, string cmdText, MySqlParameter[] cmdParms)
{
if (conn.State != ConnectionState.Open)
conn.Open();
cmd.Connection = conn;
cmd.CommandText = cmdText;
if (trans != null)
cmd.Transaction = trans;
cmd.CommandType = CommandType.Text;//cmdType;
if (cmdParms != null)
{
foreach (MySqlParameter parameter in cmdParms)
{
if ((parameter.Direction == ParameterDirection.InputOutput || parameter.Direction == ParameterDirection.Input) &&
(parameter.Value == null))
{
parameter.Value = DBNull.Value;
}
cmd.Parameters.Add(parameter);
}
}
}
#endregion
////// 执行SQL语句，返回影响的记录数 /// /// SQL语句 ///影响的记录数 public static int ExecuteSql(string SQLString, params MySqlParameter[] cmdParms) { using (MySqlConnection connection = new MySqlConnection(connectionString)) { using (MySqlCommand cmd = new MySqlCommand()) { try { PrepareCommand(cmd, connection, null, SQLString, cmdParms); int rows = cmd.ExecuteNonQuery(); cmd.Parameters.Clear(); return rows; } catch (MySql.Data.MySqlClient.MySqlException e) { throw e; } } } }
#region 执行简单SQL语句 ////// 执行SQL语句，返回影响的记录数 /// /// SQL语句 ///影响的记录数 public static int ExecuteSql(string SQLString) { using (MySqlConnection connection = new MySqlConnection(connectionString)) { using (MySqlCommand cmd = new MySqlCommand(SQLString, connection)) { try { connection.Open(); int rows = cmd.ExecuteNonQuery(); return rows; } catch (MySql.Data.MySqlClient.MySqlException e) { connection.Close(); throw e; } } } } public static int ExecuteSqlByTime(string SQLString, int Times) { using (MySqlConnection connection = new MySqlConnection(connectionString)) { using (MySqlCommand cmd = new MySqlCommand(SQLString, connection)) { try { connection.Open(); cmd.CommandTimeout = Times; int rows = cmd.ExecuteNonQuery(); return rows; } catch (MySql.Data.MySqlClient.MySqlException e) { connection.Close(); throw e; } } } } ////// 执行MySql和Oracle滴混合事务 /// /// SQL命令行列表 /// Oracle命令行列表 ///执行结果 0-由于SQL造成事务失败 -1 由于Oracle造成事务失败 1-整体事务执行成功 public static int ExecuteSqlTran(Listlist, List oracleCmdSqlList) { using (MySqlConnection conn = new MySqlConnection(connectionString)) { conn.Open(); MySqlCommand cmd = new MySqlCommand(); cmd.Connection = conn; MySqlTransaction tx = conn.BeginTransaction(); cmd.Transaction = tx; try { foreach (CommandInfo myDE in list) { string cmdText = myDE.CommandText; MySqlParameter[] cmdParms = (MySqlParameter[])myDE.Parameters; PrepareCommand(cmd, conn, tx, cmdText, cmdParms); if (myDE.EffentNextType == EffentNextType.SolicitationEvent) { if (myDE.CommandText.ToLower().IndexOf("count(") == -1) { tx.Rollback(); throw new Exception("违背要求"+myDE.CommandText+"必须符合select count(..的格式"); //return 0; } object obj = cmd.ExecuteScalar(); bool isHave = false; if (obj == null && obj == DBNull.Value) { isHave = false; } isHave = Convert.ToInt32(obj) > 0; if (isHave) { //引发事件 myDE.OnSolicitationEvent(); } } if (myDE.EffentNextType == EffentNextType.WhenHaveContine || myDE.EffentNextType == EffentNextType.WhenNoHaveContine) { if (myDE.CommandText.ToLower().IndexOf("count(") == -1) { tx.Rollback(); throw new Exception("SQL:违背要求" + myDE.CommandText + "必须符合select count(..的格式"); //return 0; } object obj = cmd.ExecuteScalar(); bool isHave = false; if (obj == null && obj == DBNull.Value) { isHave = false; } isHave = Convert.ToInt32(obj) > 0; if (myDE.EffentNextType == EffentNextType.WhenHaveContine && !isHave) { tx.Rollback(); throw new Exception("SQL:违背要求" + myDE.CommandText + "返回值必须大于0"); //return 0; } if (myDE.EffentNextType == EffentNextType.WhenNoHaveContine && isHave) { tx.Rollback(); throw new Exception("SQL:违背要求" + myDE.CommandText + "返回值必须等于0"); //return 0; } continue; } int val = cmd.ExecuteNonQuery(); if (myDE.EffentNextType == EffentNextType.ExcuteEffectRows && val == 0) { tx.Rollback(); throw new Exception("SQL:违背要求" + myDE.CommandText + "必须有影响行"); //return 0; } cmd.Parameters.Clear(); } string oraConnectionString = PubConstant.GetConnectionString("ConnectionStringPPC"); bool res = OracleHelper.ExecuteSqlTran(oraConnectionString, oracleCmdSqlList); if (!res) { tx.Rollback(); throw new Exception("执行失败"); // return -1; } tx.Commit(); return 1; } catch (MySql.Data.MySqlClient.MySqlException e) { tx.Rollback(); throw e; } catch (Exception e) { tx.Rollback(); throw e; } } } /// /// 执行多条SQL语句，实现数据库事务。 /// /// 多条SQL语句 public static int ExecuteSqlTran(ListSQLStringList) { using (MySqlConnection conn = new MySqlConnection(connectionString)) { conn.Open(); MySqlCommand cmd = new MySqlCommand(); cmd.Connection = conn; MySqlTransaction tx = conn.BeginTransaction(); cmd.Transaction = tx; try { int count = 0; for (int n = 0; n < SQLStringList.Count; n++) { string strsql = SQLStringList[n]; if (strsql.Trim().Length > 1) { cmd.CommandText = strsql; count += cmd.ExecuteNonQuery(); } } tx.Commit(); return count; } catch { tx.Rollback(); return 0; } } } /// /// 执行带一个存储过程参数的的SQL语句。 /// /// SQL语句 /// 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 ///影响的记录数 public static int ExecuteSql(string SQLString, string content) { using (MySqlConnection connection = new MySqlConnection(connectionString)) { MySqlCommand cmd = new MySqlCommand(SQLString, connection); MySql.Data.MySqlClient.MySqlParameter myParameter = new MySql.Data.MySqlClient.MySqlParameter("@content", SqlDbType.NText); myParameter.Value = content; cmd.Parameters.Add(myParameter); try { connection.Open(); int rows = cmd.ExecuteNonQuery(); return rows; } catch (MySql.Data.MySqlClient.MySqlException e) { throw e; } finally { cmd.Dispose(); connection.Close(); } } } ////// 执行带一个存储过程参数的的SQL语句。 /// /// SQL语句 /// 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 ///影响的记录数 public static object ExecuteSqlGet(string SQLString, string content) { using (MySqlConnection connection = new MySqlConnection(connectionString)) { MySqlCommand cmd = new MySqlCommand(SQLString, connection); MySql.Data.MySqlClient.MySqlParameter myParameter = new MySql.Data.MySqlClient.MySqlParameter("@content", SqlDbType.NText); myParameter.Value = content; cmd.Parameters.Add(myParameter); try { connection.Open(); object obj = cmd.ExecuteScalar(); if ((Object.Equals(obj, null)) || (Object.Equals(obj, System.DBNull.Value))) { return null; } else { return obj; } } catch (MySql.Data.MySqlClient.MySqlException e) { throw e; } finally { cmd.Dispose(); connection.Close(); } } } ////// 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) /// /// SQL语句 /// 图像字节,数据库的字段类型为image的情况 ///影响的记录数 public static int ExecuteSqlInsertImg(string strSQL, byte[] fs) { using (MySqlConnection connection = new MySqlConnection(connectionString)) { MySqlCommand cmd = new MySqlCommand(strSQL, connection); MySql.Data.MySqlClient.MySqlParameter myParameter = new MySql.Data.MySqlClient.MySqlParameter("@fs", SqlDbType.Image); myParameter.Value = fs; cmd.Parameters.Add(myParameter); try { connection.Open(); int rows = cmd.ExecuteNonQuery(); return rows; } catch (MySql.Data.MySqlClient.MySqlException e) { throw e; } finally { cmd.Dispose(); connection.Close(); } } } //////执行一条计算查询结果语句，返回查询结果(object)。 /// ///计算查询结果语句 ///查询结果（object） public static object GetSingle(string SQLString) { using (MySqlConnection connection = new MySqlConnection(connectionString)) { using (MySqlCommand cmd = new MySqlCommand(SQLString, connection)) { try { connection.Open(); object obj = cmd.ExecuteScalar(); if ((Object.Equals(obj, null)) || (Object.Equals(obj, System.DBNull.Value))) { return null; } else { return obj; } } catch (MySql.Data.MySqlClient.MySqlException e) { connection.Close(); throw e; } } } } public static object GetSingle(string SQLString, int Times) { using (MySqlConnection connection = new MySqlConnection(connectionString)) { using (MySqlCommand cmd = new MySqlCommand(SQLString, connection)) { try { connection.Open(); cmd.CommandTimeout = Times; object obj = cmd.ExecuteScalar(); if ((Object.Equals(obj, null)) || (Object.Equals(obj, System.DBNull.Value))) { return null; } else { return obj; } } catch (MySql.Data.MySqlClient.MySqlException e) { connection.Close(); throw e; } } } } ////// 执行查询语句，返回MySqlDataReader ( 注意：调用该方法后，一定要对MySqlDataReader进行Close ) /// /// 查询语句 ///MySqlDataReader public static MySqlDataReader ExecuteReader(string strSQL) { MySqlConnection connection = new MySqlConnection(connectionString); MySqlCommand cmd = new MySqlCommand(strSQL, connection); try { connection.Open(); MySqlDataReader myReader = cmd.ExecuteReader(CommandBehavior.CloseConnection); return myReader; } catch (MySql.Data.MySqlClient.MySqlException e) { throw e; } } ////// 执行查询语句，返回DataSet /// /// 查询语句 ///DataSet public static DataSet Query(string SQLString) { using (MySqlConnection connection = new MySqlConnection(connectionString)) { DataSet ds = new DataSet(); try { connection.Open(); MySqlDataAdapter command = new MySqlDataAdapter(SQLString, connection); command.Fill(ds, "ds"); } catch (MySql.Data.MySqlClient.MySqlException ex) { throw new Exception(ex.Message); } return ds; } } public static DataSet Query(string SQLString, int Times) { using (MySqlConnection connection = new MySqlConnection(connectionString)) { DataSet ds = new DataSet(); try { connection.Open(); MySqlDataAdapter command = new MySqlDataAdapter(SQLString, connection); command.SelectCommand.CommandTimeout = Times; command.Fill(ds, "ds"); } catch (MySql.Data.MySqlClient.MySqlException ex) { throw new Exception(ex.Message); } return ds; } } #endregion #region 执行带参数的SQL语句 ////// 执行SQL语句，返回影响的记录数 /// /// SQL语句 ///影响的记录数 public static int ExecuteSql(string SQLString, params MySqlParameter[] cmdParms) { using (MySqlConnection connection = new MySqlConnection(connectionString)) { using (MySqlCommand cmd = new MySqlCommand()) { try { PrepareCommand(cmd, connection, null, SQLString, cmdParms); int rows = cmd.ExecuteNonQuery(); cmd.Parameters.Clear(); return rows; } catch (MySql.Data.MySqlClient.MySqlException e) { throw e; } } } } ////// 执行多条SQL语句，实现数据库事务。 /// /// SQL语句的哈希表（key为sql语句，value是该语句的MySqlParameter[]） public static void ExecuteSqlTran(Hashtable SQLStringList) { using (MySqlConnection conn = new MySqlConnection(connectionString)) { conn.Open(); using (MySqlTransaction trans = conn.BeginTransaction()) { MySqlCommand cmd = new MySqlCommand(); try { //循环 foreach (DictionaryEntry myDE in SQLStringList) { string cmdText = myDE.Key.ToString(); MySqlParameter[] cmdParms = (MySqlParameter[])myDE.Value; PrepareCommand(cmd, conn, trans, cmdText, cmdParms); int val = cmd.ExecuteNonQuery(); cmd.Parameters.Clear(); } trans.Commit(); } catch { trans.Rollback(); throw; } } } } ////// 执行多条SQL语句，实现数据库事务。 /// /// SQL语句的哈希表（key为sql语句，value是该语句的MySqlParameter[]） public static int ExecuteSqlTran(System.Collections.Generic.ListcmdList) { using (MySqlConnection conn = new MySqlConnection(connectionString)) { conn.Open(); using (MySqlTransaction trans = conn.BeginTransaction()) { MySqlCommand cmd = new MySqlCommand(); try { int count = 0; //循环 foreach (CommandInfo myDE in cmdList) { string cmdText = myDE.CommandText; MySqlParameter[] cmdParms = (MySqlParameter[])myDE.Parameters; PrepareCommand(cmd, conn, trans, cmdText, cmdParms); if (myDE.EffentNextType == EffentNextType.WhenHaveContine || myDE.EffentNextType == EffentNextType.WhenNoHaveContine) { if (myDE.CommandText.ToLower().IndexOf("count(") == -1) { trans.Rollback(); return 0; } object obj = cmd.ExecuteScalar(); bool isHave = false; if (obj == null && obj == DBNull.Value) { isHave = false; } isHave = Convert.ToInt32(obj) > 0; if (myDE.EffentNextType == EffentNextType.WhenHaveContine && !isHave) { trans.Rollback(); return 0; } if (myDE.EffentNextType == EffentNextType.WhenNoHaveContine && isHave) { trans.Rollback(); return 0; } continue; } int val = cmd.ExecuteNonQuery(); count += val; if (myDE.EffentNextType == EffentNextType.ExcuteEffectRows && val == 0) { trans.Rollback(); return 0; } cmd.Parameters.Clear(); } trans.Commit(); return count; } catch { trans.Rollback(); throw; } } } } /// /// 执行多条SQL语句，实现数据库事务。 /// /// SQL语句的哈希表（key为sql语句，value是该语句的MySqlParameter[]） public static void ExecuteSqlTranWithIndentity(System.Collections.Generic.ListSQLStringList) { using (MySqlConnection conn = new MySqlConnection(connectionString)) { conn.Open(); using (MySqlTransaction trans = conn.BeginTransaction()) { MySqlCommand cmd = new MySqlCommand(); try { int indentity = 0; //循环 foreach (CommandInfo myDE in SQLStringList) { string cmdText = myDE.CommandText; MySqlParameter[] cmdParms = (MySqlParameter[])myDE.Parameters; foreach (MySqlParameter q in cmdParms) { if (q.Direction == ParameterDirection.InputOutput) { q.Value = indentity; } } PrepareCommand(cmd, conn, trans, cmdText, cmdParms); int val = cmd.ExecuteNonQuery(); foreach (MySqlParameter q in cmdParms) { if (q.Direction == ParameterDirection.Output) { indentity = Convert.ToInt32(q.Value); } } cmd.Parameters.Clear(); } trans.Commit(); } catch { trans.Rollback(); throw; } } } } /// /// 执行多条SQL语句，实现数据库事务。 /// /// SQL语句的哈希表（key为sql语句，value是该语句的MySqlParameter[]） public static void ExecuteSqlTranWithIndentity(Hashtable SQLStringList) { using (MySqlConnection conn = new MySqlConnection(connectionString)) { conn.Open(); using (MySqlTransaction trans = conn.BeginTransaction()) { MySqlCommand cmd = new MySqlCommand(); try { int indentity = 0; //循环 foreach (DictionaryEntry myDE in SQLStringList) { string cmdText = myDE.Key.ToString(); MySqlParameter[] cmdParms = (MySqlParameter[])myDE.Value; foreach (MySqlParameter q in cmdParms) { if (q.Direction == ParameterDirection.InputOutput) { q.Value = indentity; } } PrepareCommand(cmd, conn, trans, cmdText, cmdParms); int val = cmd.ExecuteNonQuery(); foreach (MySqlParameter q in cmdParms) { if (q.Direction == ParameterDirection.Output) { indentity = Convert.ToInt32(q.Value); } } cmd.Parameters.Clear(); } trans.Commit(); } catch { trans.Rollback(); throw; } } } } ////// 执行一条计算查询结果语句，返回查询结果（object）。 /// /// 计算查询结果语句 ///查询结果（object） public static object GetSingle(string SQLString, params MySqlParameter[] cmdParms) { using (MySqlConnection connection = new MySqlConnection(connectionString)) { using (MySqlCommand cmd = new MySqlCommand()) { try { PrepareCommand(cmd, connection, null, SQLString, cmdParms); object obj = cmd.ExecuteScalar(); cmd.Parameters.Clear(); if ((Object.Equals(obj, null)) || (Object.Equals(obj, System.DBNull.Value))) { return null; } else { return obj; } } catch (MySql.Data.MySqlClient.MySqlException e) { throw e; } } } } ////// 执行查询语句，返回MySqlDataReader ( 注意：调用该方法后，一定要对MySqlDataReader进行Close ) /// /// 查询语句 ///MySqlDataReader public static MySqlDataReader ExecuteReader(string SQLString, params MySqlParameter[] cmdParms) { MySqlConnection connection = new MySqlConnection(connectionString); MySqlCommand cmd = new MySqlCommand(); try { PrepareCommand(cmd, connection, null, SQLString, cmdParms); MySqlDataReader myReader = cmd.ExecuteReader(CommandBehavior.CloseConnection); cmd.Parameters.Clear(); return myReader; } catch (MySql.Data.MySqlClient.MySqlException e) { throw e; } // finally // { // cmd.Dispose(); // connection.Close(); // } } ////// 执行查询语句，返回DataSet /// /// 查询语句 ///DataSet public static DataSet Query(string SQLString, params MySqlParameter[] cmdParms) { using (MySqlConnection connection = new MySqlConnection(connectionString)) { MySqlCommand cmd = new MySqlCommand(); PrepareCommand(cmd, connection, null, SQLString, cmdParms); using (MySqlDataAdapter da = new MySqlDataAdapter(cmd)) { DataSet ds = new DataSet(); try { da.Fill(ds, "ds"); cmd.Parameters.Clear(); } catch (MySql.Data.MySqlClient.MySqlException ex) { throw new Exception(ex.Message); } return ds; } } } private static void PrepareCommand(MySqlCommand cmd, MySqlConnection conn, MySqlTransaction trans, string cmdText, MySqlParameter[] cmdParms) { if (conn.State != ConnectionState.Open) conn.Open(); cmd.Connection = conn; cmd.CommandText = cmdText; if (trans != null) cmd.Transaction = trans; cmd.CommandType = CommandType.Text;//cmdType; if (cmdParms != null) { foreach (MySqlParameter parameter in cmdParms) { if ((parameter.Direction == ParameterDirection.InputOutput || parameter.Direction == ParameterDirection.Input) && (parameter.Value == null)) { parameter.Value = DBNull.Value; } cmd.Parameters.Add(parameter); } } } #endregion }
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