Visual Basic 如何在显示 MsgBox 后停止事件

Question

我想确保用户在我的进一步处理之前选中了我的 3 个复选框之一，因此我创建了下面的函数，如果他们没有检查任何内容，我会生成消息。 问题是该过程在味精盒之后仍在继续。那么，在显示此特定消息框后，有没有办法停止此事件？

Private Sub btnPay_Click(sender As Object, e As EventArgs) Handles btnPay.Click
If chkbNotes.Checked = True Then
conn.Open()
sql = "UPDATE Order SET payment_method_id = 1 WHERE Id = '" + FoodMenu.OrderID + "';"
cmd = New SqlCommand(sql, conn)
cmd.ExecuteNonQuery()
Else
If chkbCreditCard.Checked = True Then
conn.Open()
sql = "UPDATE Order SET payment_method_id = 2 WHERE Id = '" + FoodMenu.OrderID + "';"
cmd = New SqlCommand(sql, conn)
cmd.ExecuteNonQuery()
Else
If chkbEwallet.Checked = True Then
conn.Open()
sql = "UPDATE Order SET payment_method_id = 2 WHERE Id = '" + FoodMenu.OrderID + "';"
cmd = New SqlCommand(sql, conn)
cmd.ExecuteNonQuery()
Else
MsgBox("Please choose 1 Payment Method", MsgBoxStyle.Exclamation, "Error")
End If
End If
End If
Dim Amount As String
Amount = InputBox("Enter Paying Amount (EX:100.00)", "Amount")
If (IsNumeric(Amount)) = True Then
.
.
.

Answer 1

下面是你的代码应该是什么样子的：

Private Sub btnPay_Click(sender As Object, e As EventArgs) Handles btnPay.Click
Dim paymentMethodId As Integer
If chkbNotes.Checked Then
paymentMethodId = 1
ElseIf chkbCreditCard.Checked Then
paymentMethodId = 2
ElseIf chkbEwallet.Checked Then
paymentMethodId = 3
Else
MessageBox.Show("Please choose 1 Payment Method", "Error", MessageBoxButtons.OK, MessageBoxIcon.Exclamation)
Return
End If
sql = "UPDATE Order SET payment_method_id = @PaymentMethodId WHERE Id = @Id"
cmd = New SqlCommand(sql, conn)
cmd.Parameters.Add("@PaymentMethodId", SqlDbType.Int).Value = paymentMethodId
cmd.Parameters.Add("@Id", SqlDbType.Int).Value = FoodMenu.OrderID
conn.Open()
cmd.ExecuteNonQuery()

我冒昧地假设，在第三种情况下，payemtn 方法 ID 应该是 3，而不是您在原始代码中使用的 2。

我还建议您更改 ADO.NEt 代码，因为您似乎正在重用连接和命令对象。您应该在需要它们的地方和时间创建和销毁它们。