C# 与MySQL
1. MySQL.Data.dll http://files.cnblogs.com/files/lwngreat/MySql.Data.rar
2.在工程中添加引用
3. 使用 MysqlHelper.cs 方便MySQL的应用
/********************************************
* MySQL数据库接口
* 文件明： MysqlHelper.cs
*******************************************/
using System;
using System.Data;
using MySql.Data.MySqlClient;
namespace DatabaseToShp
{
public class MysqlHelper
{
/// <summary>
/// 数据库连接串
/// </summary>
private string ConnString = "Database=amtiot_bak;Data Source=192.168.17.130;User Id=root;Password=sql5;pooling=false;CharSet=utf8;port=3306";
/// <summary>
/// 数据库连接
/// </summary>
private MySqlConnection Conn;
/// <summary>
/// 错误信息
/// </summary>
public static string ErrorString = "";
/// <summary>
/// 超时（秒）
/// </summary>
;
/// <summary>
/// 初始化数据库链接
/// </summary>
/// <param name="connString">数据库链接</param>
public MysqlHelper(string connString)
{
ConnString = connString;
ConnTo();
}
/// <summary>
/// 执行sql返回DataTable
/// </summary>
/// <param name="SqlString">SQL语句</param>
/// <param name="parms">Sql参数</param>
/// <returns>DataTable</returns>
public DataTable ExecuteDataTable(string SqlString, MySqlParameter[] parms)
{
if (Conn == null || Conn.State != ConnectionState.Open)
ConnTo();
try
{
MySqlCommand cmd = new MySqlCommand();
cmd.Connection = Conn;
cmd.CommandType = CommandType.Text;
cmd.CommandText = SqlString;
cmd.CommandTimeout = TimeOut;
if (parms != null)
foreach (MySqlParameter pram in parms)
cmd.Parameters.Add(pram);
DataTable dt = new DataTable();
dt.Load(cmd.ExecuteReader());
return dt;
}
catch (Exception e)
{
AddError(e.Message, SqlString);
return null;
}
}
/// <summary>
/// 返回第一行
/// </summary>
/// <param name="SqlString"></param>
/// <returns></returns>
public DataRow ExecuteDataTableRow(string SqlString, MySqlParameter[] parms)
{
if (Conn == null || Conn.State != ConnectionState.Open)
ConnTo();
try
{
MySqlCommand cmd = new MySqlCommand();
cmd.Connection = Conn;
cmd.CommandType = CommandType.Text;
cmd.CommandText = SqlString;
cmd.CommandTimeout = TimeOut;
if (parms != null)
foreach (MySqlParameter pram in parms)
cmd.Parameters.Add(pram);
DataTable dt = new DataTable();
dt.Load(cmd.ExecuteReader());
)
];
}
catch (Exception e)
{
AddError(e.Message, SqlString);
}
return null;
}
/// <summary>
/// 返回第一个值
/// </summary>
/// <param name="SqlString"></param>
/// <returns></returns>
public string ExecuteFirst(string SqlString, MySqlParameter[] parms)
{
if (Conn == null || Conn.State != ConnectionState.Open)
ConnTo();
try
{
MySqlCommand cmd = new MySqlCommand();
cmd.Connection = Conn;
cmd.CommandType = CommandType.Text;
cmd.CommandText = SqlString;
cmd.CommandTimeout = TimeOut;
if (parms != null)
foreach (MySqlParameter pram in parms)
cmd.Parameters.Add(pram);
MySqlDataReader ss = cmd.ExecuteReader();
string xx = "";
if (ss.Read())
xx = ss[].ToString();
ss.Close();
return xx;
}
catch (Exception e)
{
AddError(e.Message, SqlString);
}
return null;
}
/// <summary>
/// 返回第一个值
/// </summary>
/// <param name="SqlString"></param>
/// <returns></returns>
public long ExecuteInsertId(string SqlString, MySqlParameter[] parms)
{
if (Conn == null || Conn.State != ConnectionState.Open)
ConnTo();
try
{
MySqlCommand cmd = new MySqlCommand();
cmd.Connection = Conn;
cmd.CommandType = CommandType.Text;
cmd.CommandText = SqlString;
cmd.CommandTimeout = TimeOut;
if (parms != null)
foreach (MySqlParameter pram in parms)
cmd.Parameters.Add(pram);
cmd.ExecuteNonQuery();
return cmd.LastInsertedId;
}
catch (Exception e)
{
AddError(e.Message, SqlString);
}
;
}
/// <summary>
/// 执行无返回SQL语句
/// </summary>
/// <param name="SqlString">SQL语句</param>
/// <param name="parms">Sql参数</param>
///<returns>是否执行成功</returns>
public bool ExecuteNonQuery(string SqlString, MySqlParameter[] parms)
{
if (Conn == null || Conn.State != ConnectionState.Open)
ConnTo();
try
{
MySqlCommand cmd = new MySqlCommand();
cmd.Connection = Conn;
cmd.CommandType = CommandType.Text;
cmd.CommandText = SqlString;
cmd.CommandTimeout = TimeOut;
if (parms != null)
foreach (MySqlParameter pram in parms)
cmd.Parameters.Add(pram);
cmd.ExecuteNonQuery();
return true;
}
catch (Exception e)
{
AddError(e.Message, SqlString);
return false;
}
}
/// <summary>
/// 查询是否存在
/// </summary>
/// <param name="SqlString">SQL语句</param>
/// <param name="parms">SQL参数</param>
/// <returns>是否存在</returns>
public bool ExecuteExists(string SqlString, MySqlParameter[] parms)
{
if (Conn == null || Conn.State != ConnectionState.Open)
ConnTo();
try
{
MySqlCommand cmd = new MySqlCommand();
cmd.Connection = Conn;
cmd.CommandType = CommandType.Text;
cmd.CommandText = SqlString;
cmd.CommandTimeout = TimeOut;
if (parms != null)
foreach (MySqlParameter pram in parms)
cmd.Parameters.Add(pram);
DataTable dt = new DataTable();
dt.Load(cmd.ExecuteReader());
)
return true;
return false;
}
catch (Exception e)
{
AddError(e.Message, SqlString);
return false;
}
}
/// <summary>
/// 连接数据库
/// </summary>
private void ConnTo()
{
Close();
try
{
Conn = new MySqlConnection(ConnString);
Conn.Open();
}
catch (Exception e)
{
ErrorString += "数据库连接错误：" + e.Message + "\r\n连接串：" + ConnString + "\r\n";
)
ErrorString = null;
}
}
/// <summary>
/// 错误信息
/// </summary>
/// <param name="message"></param>
/// <param name="sql"></param>
private void AddError(string message, string sql)
{
ErrorString += "数据库连接错误：" + message + "\r\nSQL语句：" + sql + "\r\n";
)
ErrorString = "";
}
/// <summary>
/// 关闭数据库链接
/// </summary>
public void Close()
{
try
{
this.Conn.Close();
Conn = null;
}
catch
{
}
}
}
}
//DbHelperMySQL.cs、放在项目中直接使用
using System;
using System.Collections;
using System.Collections.Specialized;
using System.Data;
using MySql.Data.MySqlClient;
using System.Configuration;
using System.Data.Common;
using System.Collections.Generic;
namespace Maticsoft.DBUtility
{
/// <summary>
/// 数据访问抽象基础类
/// Copyright (C) 2004-2008 By LiTianPing
/// </summary>
public abstract class DbHelperMySQL
{
//数据库连接字符串(web.config来配置)，可以动态更改connectionString支持多数据库.
public DbHelperMySQL()
{
}
#region 公用方法
/// <summary>
/// 得到最大值
/// </summary>
/// <param name="FieldName"></param>
/// <param name="TableName"></param>
/// <returns></returns>
public static int GetMaxID(string FieldName, string TableName)
{
string strsql = "select max(" + FieldName + ")+1 from " + TableName;
object obj = GetSingle(strsql, CommandInfo.constr_r);
if (obj == null)
{
;
}
else
{
return int.Parse(obj.ToString());
}
}
/// <summary>
/// 是否存在
/// </summary>
/// <param name="strSql"></param>
/// <returns></returns>
public static bool Exists(string strSql)
{
object obj = GetSingle(strSql, CommandInfo.constr_r);
int cmdresult;
if ((Object.Equals(obj, null)) || (Object.Equals(obj, System.DBNull.Value)))
{
cmdresult = ;
}
else
{
cmdresult = int.Parse(obj.ToString());
}
)
{
return false;
}
else
{
return true;
}
}
/// <summary>
/// 是否存在（基于MySqlParameter）
/// </summary>
/// <param name="strSql"></param>
/// <param name="cmdParms"></param>
/// <returns></returns>
public static bool Exists(string strSql, params MySqlParameter[] cmdParms)
{
object obj = GetSingle(strSql, CommandInfo.constr_r, cmdParms);
int cmdresult;
if ((Object.Equals(obj, null)) || (Object.Equals(obj, System.DBNull.Value)))
{
cmdresult = ;
}
else
{
cmdresult = int.Parse(obj.ToString());
}
)
{
return false;
}
else
{
return true;
}
}
#endregion
#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, string connectionString)
{
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)
{
throw e;
}
finally
{
connection.Close();
connection.Dispose();
}
}
}
}
public static int ExecuteSqlByTime(string SQLString, int Times, string connectionString)
{
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)
{
throw e;
}
finally
{
connection.Close();
connection.Dispose();
}
}
}
}
/// <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 int ExecuteSqlTran(List<String> SQLStringList, string connectionString)
{
using (MySqlConnection conn = new MySqlConnection(connectionString))
{
conn.Open();
MySqlCommand cmd = new MySqlCommand();
cmd.Connection = conn;
MySqlTransaction tx = conn.BeginTransaction();
cmd.Transaction = tx;
try
{
;
; n < SQLStringList.Count; n++)
{
string strsql = SQLStringList[n];
)
{
cmd.CommandText = strsql;
count += cmd.ExecuteNonQuery();
}
}
tx.Commit();
return count;
}
catch
{
tx.Rollback();
;
}
finally
{
conn.Close();
conn.Dispose();
}
}
}
/// <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, string connectionString)
{
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();
connection.Dispose();
}
}
}
/// <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 object ExecuteSqlGet(string SQLString, string content, string connectionString)
{
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();
connection.Dispose();
}
}
}
/// <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, string connectionString)
{
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();
connection.Dispose();
}
}
}
/// <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, string connectionString)
{
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)
{
throw e;
}
finally
{
connection.Close();
connection.Dispose();
}
}
}
}
public static object GetSingle(string SQLString, int Times, string connectionString)
{
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)
{
throw e;
}
finally
{
connection.Close();
connection.Dispose();
}
}
}
}
/// <summary>
/// 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 )
/// </summary>
/// <param name="strSQL">查询语句</param>
/// <returns>MySqlDataReader</returns>
public static MySqlDataReader ExecuteReader(string strSQL, string connectionString)
{
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)
{
connection.Close();
connection.Dispose();
throw e;
}
//finally
//{
// connection.Clone();
// connection.Dispose();
//}
}
/// <summary>
/// 执行查询语句，返回DataSet
/// </summary>
/// <param name="SQLString">查询语句</param>
/// <returns>DataSet</returns>
public static DataSet Query(string SQLString, string connectionString)
{
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);
}
finally
{
connection.Close();
connection.Dispose();
}
return ds;
}
}
public static DataSet Query(string SQLString, int Times, string connectionString)
{
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);
}
finally
{
connection.Close();
connection.Dispose();
}
return ds;
}
}
#endregion
#region 执行带参数的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, string connectionString, 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;
}
finally
{
connection.Close();
connection.Dispose();
}
}
}
}
/// <summary>
/// 执行多条SQL语句，实现数据库事务。
/// </summary>
/// <param name="SQLStringList">SQL语句的哈希表（key为sql语句，value是该语句的MySqlParameter[]）</param>
public static void ExecuteSqlTran(Hashtable SQLStringList, string connectionString)
{
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;
}
finally
{
conn.Close();
conn.Dispose();
}
}
}
}
/// <summary>
/// 执行多条SQL语句，实现数据库事务。
/// </summary>
/// <param name="SQLStringList">SQL语句的哈希表（key为sql语句，value是该语句的MySqlParameter[]）</param>
public static int ExecuteSqlTran(System.Collections.Generic.List<CommandInfo> cmdList, string connectionString)
{
using (MySqlConnection conn = new MySqlConnection(connectionString))
{
conn.Open();
using (MySqlTransaction trans = conn.BeginTransaction())
{
MySqlCommand cmd = new MySqlCommand();
try
{
;
//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)
{
)
{
trans.Rollback();
;
}
object obj = cmd.ExecuteScalar();
bool isHave = false;
if (obj == null && obj == DBNull.Value)
{
isHave = false;
}
isHave = Convert.ToInt32(obj) > ;
if (myDE.EffentNextType == EffentNextType.WhenHaveContine && !isHave)
{
trans.Rollback();
;
}
if (myDE.EffentNextType == EffentNextType.WhenNoHaveContine && isHave)
{
trans.Rollback();
;
}
continue;
}
int val = cmd.ExecuteNonQuery();
count += val;
)
{
trans.Rollback();
;
}
cmd.Parameters.Clear();
}
trans.Commit();
return count;
}
catch
{
trans.Rollback();
throw;
}
finally
{
conn.Close();
conn.Dispose();
}
}
}
}
/// <summary>
/// 执行多条SQL语句，实现数据库事务。
/// </summary>
/// <param name="SQLStringList">SQL语句的哈希表（key为sql语句，value是该语句的MySqlParameter[]）</param>
public static void ExecuteSqlTranWithIndentity(System.Collections.Generic.List<CommandInfo> SQLStringList, string connectionString)
{
using (MySqlConnection conn = new MySqlConnection(connectionString))
{
conn.Open();
using (MySqlTransaction trans = conn.BeginTransaction())
{
MySqlCommand cmd = new MySqlCommand();
try
{
;
//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;
}
finally
{
conn.Close();
conn.Dispose();
}
}
}
}
/// <summary>
/// 执行多条SQL语句，实现数据库事务。
/// </summary>
/// <param name="SQLStringList">SQL语句的哈希表（key为sql语句，value是该语句的MySqlParameter[]）</param>
public static void ExecuteSqlTranWithIndentity(Hashtable SQLStringList, string connectionString)
{
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;
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;
}
finally
{
conn.Close();
conn.Dispose();
}
}
}
}
/// <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, string connectionString, 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;
}
finally
{
connection.Close();
connection.Dispose();
}
}
}
}
/// <summary>
/// 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 )
/// </summary>
/// <param name="strSQL">查询语句</param>
/// <returns>MySqlDataReader</returns>
public static MySqlDataReader ExecuteReader(string SQLString, string connectionString, 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)
{
connection.Close();
connection.Dispose();
throw e;
}
//finally
//{
// cmd.Dispose();
// connection.Close();
// connection.Dispose();
//}
}
/// <summary>
/// 执行查询语句，返回DataSet
/// </summary>
/// <param name="SQLString">查询语句</param>
/// <returns>DataSet</returns>
public static DataSet Query(string SQLString, string connectionString, 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);
}
finally
{
connection.Close();
connection.Dispose();
}
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
}
}
4.原理介绍
string ConnString = "Database=amtiot_bak;Data Source=192.168.17.130;User Id=root;Password=sql5;pooling=false;CharSet=utf8;port=3306";
MySqlConnection Conn = new MySqlConnection(ConnString); //1.连接数据库
Conn.Open();
MySqlCommand mySqlCommand = new MySqlCommand(SqlString, Conn); //2.构建命令
DataTable dataTable =mySqlCommand.ExecuteReader(); //3.执行命令
foreach (DataRow dataRow in dataTablePoint.Rows) //4.遍历结果
Debug.WriteLine(dataRow[]);
MySqlCommand mySqlCommand = new MySqlCommand(); //下面语句同 2步骤作用相同
mySqlCommand.Connection = Conn;
mySqlCommand.CommandText = SqlString;
mySqlCommand.ExecuteReader()
一些很用用的帮助类文件：http://tool.sufeinet.com/CodePreview/CodeView.aspx
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