SQL to include condition in Where if not null

问题

In access I have been trying to set up user filters on what is displayed in a subform which is a list of inspection. Other methods Ive tried looking into have not been working but I have success with the below code, It will filter if a user fills any other the filter options. What I can figure out is how to have it accept multiple filters unless I spelt out every possible combination of boxes

So is there anyway this is actually possible or do I need to look at other options?

WHERE [STATUS] = "OPEN" 
AND 
(ANY FORM FILTERS is not Null [Filter by all those that are not null to its matching column])

effectively is there any easy way to include a condition if a form filter is not null

SELECT Inspections.INS_ID
    ,Inspections.Category
    ,Inspections.Assigned_Officer
    ,Inspections.Raised_For
    ,Inspections.Account
    ,Inspections.Number
    ,Inspections.Street
    ,Inspections.Area
    ,Inspections.Postcode
    ,Inspections.Date_Raised
    ,Inspections.Reason
    ,Inspections.INS_Comments
FROM Inspections
WHERE (
        ((Inspections.STATUS) = "Open")
        AND (([Forms]![Manage_Open]![Filter_ID]) IS NULL)
        AND (([Forms]![Manage_Open]![Filter_account]) IS NULL)
        AND (([Forms]![Manage_Open]![Filter_officer]) IS NULL)
        AND (([Forms]![Manage_Open]![Filter_Number]) IS NULL)
        AND (([Forms]![Manage_Open]![Filter_Postcode]) IS NULL)
        AND (([Forms]![Manage_Open]![Filter_Category]) IS NULL)
        AND (
            (([Forms]![Manage_Open]![Filter_From]) IS NULL)
            AND (([Forms]![Manage_Open]![Filter_To]) IS NULL)
            )
        )
    OR (
        ([Forms]![Manage_Open]![Filter_ID]) IS NOT NULL
        AND ([Forms]![Manage_Open]![Filter_ID]) = [Inspections].[INS_ID]
        )
    OR (
        ([Forms]![Manage_Open]![Filter_account]) IS NOT NULL
        AND ([Forms]![Manage_Open]![Filter_account]) = [Inspections].[Account]
        )
    OR (
        ([Forms]![Manage_Open]![Filter_officer]) IS NOT NULL
        AND ([Forms]![Manage_Open]![Filter_officer]) = [Inspections].[Assigned_Officer]
        )
    OR (
        ([Forms]![Manage_Open]![Filter_Number]) IS NOT NULL
        AND ([Forms]![Manage_Open]![Filter_Number]) = [Inspections].[Number]
        )
    OR (
        ([Forms]![Manage_Open]![Filter_Postcode]) IS NOT NULL
        AND ([Forms]![Manage_Open]![Filter_Postcode]) = [Inspections].[Postcode]
        )
    OR (
        ([Forms]![Manage_Open]![Filter_Category]) IS NOT NULL
        AND ([Forms]![Manage_Open]![Filter_Category]) = [Inspections].[Category]
        )
    OR (
        (
            (([Forms]![Manage_Open]![Filter_From]) IS NOT NULL)
            AND (([Forms]![Manage_Open]![Filter_To]) IS NOT NULL)
            )
        AND ([Inspections].[Raised_For]) BETWEEN (
                    ([Forms]![Manage_Open]![Filter_From])
                    AND ([Forms]![Manage_Open]![Filter_to])
                    ) )
        );

回答1:

If I understand correctly, you have a form with several unbound controls that the user will fill in. You, then want to filter your subform according to what the user has entered. In that case, the method you are trying to use will become very complex and difficult to maintain, not to mention slow with a lot of data. The best bet is to build the filter in code. What I often do is name the controls the same as the field name and put the field type in the control's tag property. Then loop through the controls to build the filter. This is air code, but should give you a start. Dim strFilter as string Dim ctL as Access.control For Each ctL in Me.Controls If Not ISNull(ctL) And ctL.Tag <> "" Then strFilter = strFilter & " AND " & ctl.Name & " = " If ctL.Tag = "Text" Then strFilter = strFilter & "'" & Replace(ctl, "'","''") & "'" ElseIf ctL.Tag = "Date" Then strFilter = strFilter & "#" & ctl & "#" Else strFilter = strFilter & ctlEnd If Next If strFilter <> "" Then strFilter = mid(strFilter, 6) strFilter = " Where " & strFilter End If Me.yourSubForm.Form.Recordsource = "Select * From <yourQuery> " & strfilter

来源：https://stackoverflow.com/questions/44654449/sql-to-include-condition-in-where-if-not-null