異常：
[InvalidOperationException: 無效操作。連接被關閉。]
System.Data.ProviderBase.DbConnectionClosed.BeginTransaction(IsolationLevel il) +11
System.Data.OleDb.OleDbConnection.BeginTransaction(IsolationLevel isolationLevel) +13
System.Data.OleDb.OleDbConnection.BeginTransaction() +7
VideoWorld.LibDAO.CardChargeDAO.getCharged(Int32 userId, String cardNumber) in D:/我的
文檔/Visual Studio 2008/Projects/VideoWorld/LibDAO/CardChargeDAO.cs:61
VideoWorld.BLL.WebFrontMoneySupplyBLL.getChargedBLL(Int32 cardId, String cardNumber)
in D:/我的文檔/Visual Studio 2008/Projects/VideoWorld/BLL/WebFrontMoneySupplyBLL.cs:35
front_moneySupply.goToPay_Click(Object sender, EventArgs e) +63
System.Web.UI.WebControls.Button.OnClick(EventArgs e) +111
System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument) +110
System.Web.UI.WebControls.Button.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent
(String eventArgument) +10
System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String
eventArgument) +13
System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) +36
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean
includeStagesAfterAsyncPoint) +1565
//創建數據庫連接
OleDbConnection connection = new OleDbConnection(ConnectString.getConnectString());
之後添加判斷：
if (connection.State != ConnectionState.Open)
connection.Open();
關閉數據庫添加判斷：
try{
}catch{
}finally{
if
(connection.State != ConnectionState.Closed) { connection.Close();
}
}
