Question

我已经编写了下面的代码来删除多个数据库表中的记录，但是一些代码如何不删除任何记录并且也不显示任何错误！有人可以帮忙吗？

    Private Sub btndelete_Click(sender As Object, e As EventArgs) Handles btndelete.Click
        Try
       cmd = New SqlCommand("IF EXISTS(SELECT * FROM book WHERE isbn = @isbn) " _
    & " BEGIN " _
    & " delete from published_by where isbn = @isbn; " _
    & " delete from return where isbn = @isbn; " _
    & " delete from issue where isbn = @isbn; " _
    & " delete from book where isbn = @isbn;" _
    & " SELECT 1; " _
    & " END " _
    & " ELSE SELECT 0", cn)
            cmd.Parameters.Add(New SqlParameter("@isbn", SqlDbType.VarChar, 13) _ 
 With {.Value = isbn})
            If cn.State = ConnectionState.Closed Then
                cn.Open()
            End If
            Dim returnValue As Integer = CInt(cmd.ExecuteScalar())
            If returnValue = 1 Then
                lblAlert.Text = ""
                lblInfo.Text = "Deleted"
            Else
                lblAlert.Text = "No Record Available"
                lblInfo.Text = ""
            End If
        Catch sqlEx As SqlException
            Select sqlEx.Number
                Case -1, 2, 53
                    MessageBox.Show("Connection Failed to Database")
            End Select
        Catch ex As Exception
            MessageBox.Show(ex.Message)
        End Try
    End If
End Sub

Answer 1

＆＃34;返回＆＃34;是一个保留字（见this reference）。要解决此问题，请将其放在如下所示的方括号中：

delete from [return] where isbn ...

关于您的代码的另一个注意事项是，如果错误编号不是-1,2或53，您正在吞咽SqlException。要解决此问题，请处理不是这些数字之一的情况这样：

Select Case sqlEx.Number
    Case -1, 2, 53
        Console.WriteLine("Connection Failed to Database")
    Case Else
        Console.WriteLine(....) 'write something here, you can use sqlEx.Message
End Select

这就是您首先没有收到错误消息的原因。

使用VB.net表单中的SQL存储过程删除记录

1 个答案: