限制多选列表框中的选择数量

Question

有没有办法限制用户在 Access 2003 中启用了多选功能的列表框中可以选择的选项数量？现在，我有一个在“单击”事件上触发的过程，该过程检查所选选项的数量，如果超过我的阈值，它将显示一个警告标签。

Answer 1

尝试一下。如果最后选择的项目超过预定义的限制，它基本上会取消选择：

Private Sub ListBox1_Change()

Dim counter         As Integer
Dim selectedCount   As Integer

selectedCount = 0

For counter = 1 To ListBox1.ListCount Step 1
    If ListBox1.Selected(counter - 1) = True Then 'selected method has 0 base
        selectedCount = selectedCount + 1
    End If
Next counter

If selectedCount >= 4 Then 'modify # here
    ListBox1.Selected(ListBox1.ListIndex) = False 'listindex returns the active row you just selected
    MsgBox "Limited to 4 Choices", vbInformation + vbOKOnly, "Retry:"
End If
End Sub