通过Connector/NET与MySQL结合使用C# [英] C# with MySQL through Connector/NET

查看：98
本文介绍了通过Connector/NET与MySQL结合使用C#的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

我正在C#(4.0 Framework)中开发CMS应用程序，该应用程序连接到远程服务器上的MySQL数据库(5.0.95) 通过MySQL Connector(6.5.4).

I'm developing CMS application in C#(4.0 Framework) which connects to MySQL database (5.0.95) on remote server by MySQL Connector (6.5.4).

我在执行查询时遇到问题.

I have problem with executing queries.

例如 我的连接字符串:

e.g. My connection string:

"Server=" + Options.DbServer + ";Database="+ Options.Database +";Uid=" + Options.DbUser + ";Pwd=" + Options.DbPassword + ";CharSet=utf8; Connect Timeout=30;";

我有管理数据库相关内容的静态类，并且我有私有成员_connection.

I have static class which manages database related stuff, and there I have private member _connection.

private static MySqlConnection _connection;
public static MySqlConnection Connection
{ 
    get
    {
        if (_connection.State != ConnectionState.Open)
            _connection.Open();

        return _connection;
    } 
    set { _connection = value; }
}

这是初始化连接的方法:

This is method which initializes connection:

public static bool Init(string cs)
{
    _connection = new MySqlConnection(cs);
    MySqlCommand command = new MySqlCommand("SET NAMES utf8", Connection);
    command.ExecuteNonQuery();
    return true;
}

这是我得到异常的方法:

This is method where I get exception:

public static bool InsertRecord(MySqlCommand command)
{
    command.Connection = Connection;
    if(command.ExecuteNonQuery() > 0)
        return true;

    return false;
}

command.ExecuteNonQuery()引发异常:命令执行期间遇到致命错误.

command.ExecuteNonQuery() throws exception: Fatal error encountered during command execution.

这是堆栈跟踪... 

MySql.Data.MySqlClient.MySqlException was unhandled
  Message=Fatal error encountered during command execution.
  Source=MySql.Data
  ErrorCode=-2147467259
  Number=0
  StackTrace:
       at MySql.Data.MySqlClient.MySqlCommand.ExecuteReader(CommandBehavior behavior)
       at MySql.Data.MySqlClient.MySqlCommand.ExecuteNonQuery()
       at CMS.Database.InsertRecord(MySqlCommand command) in C:\_myStuff\VS2010\CMS\CMS\Database.cs:line 95
       at CMS.frmAddItem.btnDo_Click(Object sender, EventArgs e) in C:\_myStuff\VS2010\CMS\CMS\frmAddItem.cs:line 138
       at System.Windows.Forms.Control.OnClick(EventArgs e)
       at System.Windows.Forms.Button.OnClick(EventArgs e)
       at System.Windows.Forms.Button.OnMouseUp(MouseEventArgs mevent)
       at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
       at System.Windows.Forms.Control.WndProc(Message& m)
       at System.Windows.Forms.ButtonBase.WndProc(Message& m)
       at System.Windows.Forms.Button.WndProc(Message& m)
       at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
       at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
       at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
       at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG& msg)
       at System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(IntPtr dwComponentID, Int32 reason, Int32 pvLoopData)
       at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)
       at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)
       at System.Windows.Forms.Application.RunDialog(Form form)
       at System.Windows.Forms.Form.ShowDialog(IWin32Window owner)
       at System.Windows.Forms.Form.ShowDialog()
       at CMS.frmMain.btnNovi_Click(Object sender, EventArgs e) in C:\_myStuff\VS2010\CMS\CMS\frmMain.cs:line 381
       at System.Windows.Forms.Control.OnClick(EventArgs e)
       at System.Windows.Forms.Button.OnClick(EventArgs e)
       at System.Windows.Forms.Button.OnMouseUp(MouseEventArgs mevent)
       at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
       at System.Windows.Forms.Control.WndProc(Message& m)
       at System.Windows.Forms.ButtonBase.WndProc(Message& m)
       at System.Windows.Forms.Button.WndProc(Message& m)
       at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
       at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
       at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
       at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG& msg)
       at System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(IntPtr dwComponentID, Int32 reason, Int32 pvLoopData)
       at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)
       at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)
       at System.Windows.Forms.Application.RunDialog(Form form)
       at System.Windows.Forms.Form.ShowDialog(IWin32Window owner)
       at System.Windows.Forms.Form.ShowDialog()
       at CMS.frmLogin.DoLogin() in C:\_myStuff\VS2010\CMS\CMS\frmLogin.cs:line 55
       at CMS.frmLogin.button2_Click(Object sender, EventArgs e) in C:\_myStuff\VS2010\CMS\CMS\frmLogin.cs:line 31
       at System.Windows.Forms.Control.OnClick(EventArgs e)
       at System.Windows.Forms.Button.OnClick(EventArgs e)
       at System.Windows.Forms.Button.OnMouseUp(MouseEventArgs mevent)
       at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
       at System.Windows.Forms.Control.WndProc(Message& m)
       at System.Windows.Forms.ButtonBase.WndProc(Message& m)
       at System.Windows.Forms.Button.WndProc(Message& m)
       at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
       at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
       at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
       at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG& msg)
       at System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(IntPtr dwComponentID, Int32 reason, Int32 pvLoopData)
       at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)
       at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)
       at System.Windows.Forms.Application.Run(Form mainForm)
       at CMS.Program.Main() in C:\_myStuff\VS2010\CMS\CMS\Program.cs:line 18
       at System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args)
       at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
       at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
       at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean ignoreSyncCtx)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
       at System.Threading.ThreadHelper.ThreadStart()
  InnerException: MySql.Data.MySqlClient.MySqlException
       Message=Fatal error encountered attempting to read the resultset.
       Source=MySql.Data
       ErrorCode=-2147467259
       Number=0
       StackTrace:
            at MySql.Data.MySqlClient.MySqlDataReader.NextResult()
            at MySql.Data.MySqlClient.MySqlCommand.ExecuteReader(CommandBehavior behavior)
       InnerException: MySql.Data.MySqlClient.MySqlException
            Message=Reading from the stream has failed.
            Source=MySql.Data
            ErrorCode=-2147467259
            Number=0
            StackTrace:
                 at MySql.Data.MySqlClient.MySqlStream.LoadPacket()
                 at MySql.Data.MySqlClient.MySqlStream.ReadPacket()
                 at MySql.Data.MySqlClient.NativeDriver.GetResult(Int32& affectedRow, Int32& insertedId)
                 at MySql.Data.MySqlClient.Driver.GetResult(Int32 statementId, Int32& affectedRows, Int32& insertedId)
                 at MySql.Data.MySqlClient.Driver.NextResult(Int32 statementId, Boolean force)
                 at MySql.Data.MySqlClient.MySqlDataReader.NextResult()
            InnerException: System.IO.EndOfStreamException
                 Message=Attempted to read past the end of the stream.
                 Source=MySql.Data
                 StackTrace:
                      at MySql.Data.MySqlClient.MySqlStream.ReadFully(Stream stream, Byte[] buffer, Int32 offset, Int32 count)
                      at MySql.Data.MySqlClient.MySqlStream.LoadPacket()
                 InnerException:

有什么建议吗?

推荐答案

我注意到您打开了连接，但是在完成连接后并没有关闭它们.我更喜欢在需要时打开连接的方法，而不是在尚未打开时打开它们的方法.它们可能是陈旧的.

I notice that you open connections, but you don't close them when you are done with them. I prefer the approach of opening connections when they are needed, rather than possibly opening them if they are not already open. They may be stale.

缓存连接字符串，但不缓存连接本身.

Cache the connection string but not the connection itself.

public static string ConnectionString {get;set;}

public static bool InsertRecord(sql)
{
    bool success = false;
    using (var con = new Connection(ConnectionString)){
        var command = new SqlCommand(sql,con);
        success = (command.ExecuteNonQuery() > 0);
    }
    return success;
}

当不再需要资源时，应将其释放.

Resources should be freed when they are no longer required.

这篇关于通过Connector/NET与MySQL结合使用C#的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！

查看全文
相关文章
C#/.NET最新文章
热门教程
热门工具
登录 关闭
扫码关注1秒登录
发送“验证码”获取 | 15天全站免登陆