MS Access查询:检查表单是否打开/检查参数是否需要输入 [英] MS Access Query : Check if form is open / Check if parameter requires input

问题描述

我目前正在尝试在MS Access查询(使用GUI工具而非SQL工具)中，而不使用VBA来检查是否打开了特定表单.

I'm currently trying, in a MS Access Query (using the GUI tool, and not the SQL tool), to check if a specific form is open or not, without using VBA.

使用以下表达式:

Expr1 : [Formulaires]![Form1].[Visible]

如果打开了Form1，则查询工作正常，但是如果关闭了Form1，则它会要求输入，因为Form1没有打开，并且该变量不再存在.

If Form1 is open, the query works fine, but if Form1 is closed, it asks for input, since the Form1 isn't open, and the variable doesn't exist anymore.

是否可以检查是否打开了特定的表单，或者检查某个变量是否需要输入?

Is there a way to check if a specific form is open, or to check if a certain variable requires input ?

推荐答案

您将需要VBA函数来发现此问题，但是您可以从查询中调用该函数并将结果合并到公式中.

You would need a VBA function to discover this but you could call the function from your query and incorporate the result in your formula.

如果加载了表单，此函数将返回true；

This function will return true if the form is loaded;

Function IsFormLoaded(strForm As String) As Boolean

Dim frm As Form

For Each frm In Forms
    If frm.Name = strForm Then
        IsFormLoaded = True
        Exit Function
    End If
Next

End Function

然后您可以在IIF语句中使用该函数；

You can then use the function in an IIF statement;

IIF(IsFormLoaded('MyForm'), MyForm.Control.Value, '')

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