C#MysqlHelper

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MysqlHelper类 
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; 
using System.Text.RegularExpressions; 
namespace LOAF.DAL 
{ 
public class MysqlHelper 
{ 
//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 static string connectionString = ConfigurationManager.ConnectionStrings["ConnDB"].ConnectionString; 
public static string connectionString = ConfigurationManager.AppSettings["MySQL"]; 
//public string m = ConfigurationManager.AppSettings["MySQL"]; 
public MysqlHelper() { } 
#region ExecuteNonQuery 
//执行SQL语句，返回影响的记录数 
/// <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 ExecuteNonQuery(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; 
} 
} 
} 
} 
/// <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 ExecuteNonQuery(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。 
/// <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 bool ExecuteNoQueryTran(List<String> SQLStringList) 
{ 
using (MySqlConnection conn = new MySqlConnection(connectionString)) 
{ 
conn.Open(); 
MySqlCommand cmd = new MySqlCommand(); 
cmd.Connection = conn; 
MySqlTransaction tx = conn.BeginTransaction(); 
cmd.Transaction = tx; 
try 
{ 
for (int n = 0; n < SQLStringList.Count; n++) 
{ 
string strsql = SQLStringList[n]; 
if (strsql.Trim().Length > 1) 
{ 
cmd.CommandText = strsql; 
PrepareCommand(cmd, conn, tx, strsql, null); 
cmd.ExecuteNonQuery(); 
} 
} 
cmd.ExecuteNonQuery(); 
tx.Commit(); 
return true; 
} 
catch 
{ 
tx.Rollback(); 
return false; 
} 
} 
} 
#endregion 
#region ExecuteScalar 
/// <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 ExecuteScalar(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; 
} 
} 
} 
} 
/// <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 ExecuteScalar(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; 
} 
} 
} 
} 
#endregion 
#region ExecuteReader 
/// <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) 
{ 
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; 
} 
} 
/// <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, 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(); 
// } 
} 
#endregion 
#region ExecuteDataTable 
/// <summary> 
/// 执行查询语句，返回DataTable 
/// </summary> 
/// <param name="SQLString">查询语句</param> 
/// <returns>DataTable</returns> 
public static DataTable ExecuteDataTable(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.Tables[0]; 
} 
} 
/// <summary> 
/// 执行查询语句，返回DataSet 
/// </summary> 
/// <param name="SQLString">查询语句</param> 
/// <returns>DataTable</returns> 
public static DataTable ExecuteDataTable(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.Tables[0]; 
} 
} 
} 
//获取起始页码和结束页码 
public static DataTable ExecuteDataTable(string cmdText, int startResord, int maxRecord) 
{ 
using (MySqlConnection connection = new MySqlConnection(connectionString)) 
{ 
DataSet ds = new DataSet(); 
try 
{ 
connection.Open(); 
MySqlDataAdapter command = new MySqlDataAdapter(cmdText, connection); 
command.Fill(ds, startResord, maxRecord, "ds"); 
} 
catch (MySql.Data.MySqlClient.MySqlException ex) 
{ 
throw new Exception(ex.Message); 
} 
return ds.Tables[0]; 
} 
} 
#endregion 
/// <summary> 
/// 获取分页数据 在不用存储过程情况下 
/// </summary> 
/// <param name="recordCount">总记录条数</param> 
/// <param name="selectList">选择的列逗号隔开,支持top num</param> 
/// <param name="tableName">表名字</param> 
/// <param name="whereStr">条件字符 必须前加 and</param> 
/// <param name="orderExpression">排序 例如 ID</param> 
/// <param name="pageIdex">当前索引页</param> 
/// <param name="pageSize">每页记录数</param> 
/// <returns></returns> 
public static DataTable getPager(out int recordCount, string selectList, string tableName, string whereStr, string orderExpression, int pageIdex, int pageSize) 
{ 
int rows = 0; 
DataTable dt = new DataTable(); 
MatchCollection matchs = Regex.Matches(selectList, @"top\s+\d{1,}", RegexOptions.IgnoreCase);//含有top 
string sqlStr = sqlStr = string.Format("select {0} from {1} where 1=1 {2}", selectList, tableName, whereStr); 
if (!string.IsNullOrEmpty(orderExpression)) { sqlStr += string.Format(" Order by {0}", orderExpression); } 
if (matchs.Count > 0) //含有top的时候 
{ 
DataTable dtTemp = ExecuteDataTable(sqlStr); 
rows = dtTemp.Rows.Count; 
} 
else //不含有top的时候 
{ 
string sqlCount = string.Format("select count(*) from {0} where 1=1 {1} ", tableName, whereStr); 
//获取行数 
object obj = ExecuteScalar(sqlCount); 
if (obj != null) 
{ 
rows = Convert.ToInt32(obj); 
} 
} 
dt = ExecuteDataTable(sqlStr, (pageIdex-1)*pageSize, pageSize); 
recordCount = rows; 
return dt; 
} 
#region 创建command 
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 
} 
}

需要注意的地方有如下几点
1）在sqlserver中参数化sql语句是用“@”符号，在mysql里面需要是用？号，切记，切记.
2 ）还有就是sqlserver中删除表可以这样写delete news where ID=12，但是在mysql里面 是delete from news where ID=12，收了from报错
3 ）我在使用过程中遇到了中文乱码，网上大部分解决办法是把表的设置成utf-8字符集。以及 C:\Program Files\MySQL\MySQL Server 5.1路径下my.ini 打开找到两处
default-character-set 都设置成=utf8。

评论

1 楼 异彩飞天 2014-08-24  

请问连接字符串怎么写？