C#winform建立一个共用的数据库连接

using   System;
using   System.Xml;
using   System.Data.OleDb;
using   System.Data;

namespace   ACS
{
///   <summary>
///   對數據庫進行更新
///   </summary>
///   AIDU數據庫連接
///   Retrieval   返回查詢Dataset
///   Translation與數據庫進行交易[Access   =   true][fail   =   false]
///

public   class   AIDU
{

#region   連接失敗返回失敗消息--[Link   Ok   return   null][Link   fail   return   ErrorMessage]
public   string   ErrorMsg()
{
return   sErrorMsg;
}

#endregion

#region   設置公共連接對像字串--[   sAcsCon   ]
public   string   sAcsConString()
{
string   sConString   =   "Provider=Microsoft.Jet.OLEDB.4.0;Data   Source   ="+@"KSZH.mdb";
// string   sConString   =   "Provider=OraOLEDB.Oracle.1;Password=mes_ks1;Persist   Security   Info=True;User   ID=mes_ks1;Data   Source=linux;Extended   Properties=";
return   sConString;
}

public   string   sAcsCon
{
get{return   sAcsConString();}
}

#endregion

#region   設置公共連接對像--[   Link_cn   ]

public   OleDbConnection   Link_cn
{
get{return   Acs_cn();}
}

public   OleDbConnection   Acs_cn()
{
OleDbConnection   cn   =   new   OleDbConnection(sAcsCon);
if(cn.State   ==   ConnectionState.Closed)
{
cn.Open();
}
return   cn;
}

#endregion

//連接失敗後的返回消息
private   string   sErrorMsg   =""   ;
//連接標志變量   [bFlag   =   true   Connection   Database   Success]
//[bFlag   =   false   Connection   Database   unSuccess]
private   bool   bFlag   =   false;

#region   數據庫連接--[   LINK-TEST   ]

public   bool   AIDU_Link()
{
OleDbConnection   TestCn   =   new   OleDbConnection(sAcsCon);
//測試數據庫連接
try
{
if(TestCn.State   !=   ConnectionState.Open)
{
TestCn.Open();
bFlag   =   true;
}
}
catch(Exception   e)
{
sErrorMsg   =   e.Message;
}
finally
{
if(TestCn.State   ==   ConnectionState.Open)
{
TestCn.Close();
}
}
return   bFlag;
}

#endregion

#region   資料查詢--[   SELECT   ]
public   DataSet   Select(string   sCmdString)
{
//建立CONNECTION對像
OleDbConnection   cn1=new   OleDbConnection(sAcsCon);
//建立DATASET對像,做資料返回值
DataSet   oDs   =   new   DataSet();
try
{//建立Adapter對像
OleDbDataAdapter   myAdapter   =   new   OleDbDataAdapter(sCmdString,cn1);
myAdapter.Fill(oDs);
}
catch
{
cn1.Close();
}

return   oDs;
}
#endregion

#region   數據資料更新--[   Update   ]

//執行--[   UPDATE   ][   INSERT   ][   DELETE   ]
//[   The   command   Execute   sccess   return   1]
//[   The   command   Execute   unSuccess   return   -1]
public   int   UpdateCmd(string   CommandString)
{
int   nResult   =   -1;
//進行一個本地交易
// OleDbTransaction   myTran   =   Link_cn.BeginTransaction(IsolationLevel.ReadCommitted);
// myTran.Begin();
//oledbcommand   命令執行交易
OleDbCommand   myCmd   =   new   OleDbCommand(CommandString,Link_cn);

//和數據庫進這行數據交易
try
{
//提交數據
myCmd.ExecuteNonQuery();
// myTran.Commit();
nResult   =   1;
}
catch(OleDbException   oe)
{
//出錯數據回滾原來的狀態，保持數據庫一致性
// myTran.Rollback();
nResult   =   -1;
throw   oe;
}
finally
{
//執行交易後關閉聯接
Link_cn.Close();
}
return   nResult;
}
#endregion
}

#region   處理字符,以符合SQL語句用--[   class   sTringAdd   ]
public   class   sTringAdd
{

public   sTringAdd(){}

public   string   SQLQ(string   sText)
{
sText   =   "'"+sText+"'";
return   sText;
}

public   string   SQLQ(int   n)
{
return   n.ToString();
}

public   string   SQLQ(double   n)
{
return   n.ToString();
}

public   string   SQLQC(string   sText)
{
sText   =   "'"+sText+"',";
return   sText;
}

public   string   SQLQC(int   nText)
{
string   sText   =   nText.ToString()+",";
return   sText;
}

public   string   SQLQC(double   nText)
{
string   sText   =   nText.ToString()+",";
return   sText;
}
}
#endregion

}