在 Select 指令後, 依據結果做一些工作, 即使有 Transaction, 但還是有可能發生一致性的問題:

Ex:

        Dim Conn As SqlConnection = UW.SQL.GetOpenedConnection

        Dim Tran As SqlTransaction = Conn.BeginTransaction

        Try

            Dim C As Int32 = UW.SQL.GetSingleValue("Select Counter From TableA Where Id = 1", Tran)

            C = C + 1

            UW.SQL.executeSQL("Update TableA Set Counter = " & C & " Where  Id = 1", Tran)

            Tran.Commit()

        Catch ex As Exception

            Tran.Rollback()

            UW.WU.DebugWriteLine(ex.ToString, True, True)

        Finally

            If Conn.State <> ConnectionState.Closed Then

                Conn.Close()

            End If

        End Try

以上的程式由兩個 Session 同時執行時, 並不能保証 Counter 會被加 2

若是要保証兩個 Session 都會把 Counter 加一(總共加 2), 要把以下這一行

Dim C As Int32 = UW.SQL.GetSingleValue("Select Counter From TableA Where Id = 1", Tran)

改為

Dim C As Int32 = UW.SQL.GetSingleValue("Select Counter From TableA With(XLock) Where Id = 1", Tran)