附加信息无效的操作。连接已关闭。
it1352
帮助1人
问题说明
我在数据库中有两个表。我正在使用这些表来探索事务，插入，更新，删除，回滚和提交的应用程序。我有四个文本框两个到每个表和一个命令
按钮。我试图插入这些表并得到以下"附加信息：无效的操作。连接已关闭。 "带下划线的声明中的例外情况。我将非常感谢所有帮助。我的代码是
显示在下面
Private Sub btnTransaction_Click(sender As Object, e As EventArgs) Handles btnTransaction.Click
Using connection As New OleDbConnection(connstr)
Dim Cmd As New oledbCommand
Dim transaction As oledbtransaction
'connection to New oledb Connection
Cmd.connection = connection
'open connection and execute transaction
Try
connection.open()
Catch ex As Exception
'Start Local connection
transaction = connection.BeginTransaction(IsolationLevel.ReadCommitted)
'assign transaction Object to local
Cmd.connection = connection
Cmd.Transaction = transaction
'execute the commands
Cmd.commandtext = "INSERT INTO RelInfo(Surname, FirstName) Value (@SName, @FName)"
Cmd.Parameters.AddWithValue("@SName", txtSurname.Text)
Cmd.Parameters.AddWithValue("@FName", txtFirstName.Text)
Cmd.ExecuteNonQuery()
Cmd.CommandText = "INSERT INTO StudentInfo(SName, FName) Value (@SName, @FName)"
Cmd.Parameters.AddWithValue("@SName", txtSName.Text)
Cmd.Parameters.AddWithValue("@FName", txtFName.Text)
Cmd.ExecuteNonQuery()
'commit transaction
transaction.Commit()
MsgBox("Both Records Are Written to the database")
Console.WriteLine(ex.Message)
'Try to rollback the transaction
Try
transaction.Rollback()
Catch
' do nothing transaction is not active anymore
End Try
End Try
End Using
Dim response As DialogResult = MessageBox.Show("Already been executed." &
Environment.NewLine & _
"Proceed with transaction?", "Performing transanction", _
MessageBoxButtons.YesNo)
End Sub
End Class正确答案
#1
为什么你在catch中有所有代码然后在catch中有另一个try catch，它没有意义。我读这个的方式，如图所示进入catch，必须在外部try中抛出一个异常。
Why do you have all the code in the catch then have another try catch in that catch, it does not make sense. The way I read this, to enter the catch as shown there must be an exception thrown in the outer try.
这篇好文章是转载于：学新通技术网
