Access Hangs on Subform recordsource set to SQL from VBA

Question

I have a "Search" form in my database that takes in a string, explodes it into an array and builds an SQL string based on a selected join type ("Or", "And", or "Exact Phrase" radio buttons). My code works perfectly 95% of the time, but every once and while the database hangs when I switch between the different join types and requery. I have confirmed that the SQL is being created properly and I think that the problem stems from trying to change the subform's recordsource while it is still loading.

The exact way that my search form works is as follows:

1. The user puts a search term/phrase in a text box
2. On the "After Update" event of the textbox, VBA creates an SQL string and stores it in a hidden text field (dubbed "ModifiedSearchValue")
3. If the user changes the join type (radiobuttons with options "Or", "And", Or "Exact Phrase") the "After Update" event on the group evokes the VBA sub (as in #2) and VBA creates an SQL string which it stores in the hidden text field (dubbed "ModifiedSearchValue")

4. When the user hits the "Search" button, VBA sets the RecordSource of the subform to the value of "ModifiedSearchValue" by:

   Me!Results.Form.RecordSource = Me.ModifiedSearchValue

Again, this works perfectly most of the time, but if you enter the search term, click "Search", then change the join type and hit "Search" again, it causes the database to hang approximately 5% of the time.

My main VBA code is as follows

    Private Sub SearchString()
Dim SearchString, SearchStringTitle, SearchStringName, SearchStringDescription, SearchStringInvestigator, JoinValue, j, SQLString As String, SearchArray, varValue As Variant

    SearchString = Trim(Me.SearchValue)

    If Not IsNull(SearchString) Then
        SearchArray = Split(SearchString, " ")

        SQLString = "SELECT tbl_Studies.StudyID, tbl_Studies.Study_Short_Title, tbl_Studies.Study_Name, tbl_Studies.Study_Description, [qry_General:FullName_FMLD].FullName AS Investigator, tbl_Studies.Project_Type, IIf([Project_Type]=1,[tbl_Studies:Status]![Status],[tbl_Studies:NR_Status]![NR_Status]) AS Overall_Status, tbl_Studies.Date_Submitted, tbl_Studies.Date_Updated, tbl_Studies.Results_Summary, tbl_Studies.Inactive " & _
                    "FROM ([tbl_Studies:NR_Status] RIGHT JOIN ([tbl_Studies:Status] RIGHT JOIN tbl_Studies ON [tbl_Studies:Status].StatusID = tbl_Studies.Status) ON [tbl_Studies:NR_Status].NR_StatusID = tbl_Studies.NR_Status) LEFT JOIN [qry_General:FullName_FMLD] ON tbl_Studies.Investigator = [qry_General:FullName_FMLD].PersonID " & _
                    "WHERE "

        If Me.Join_Type <> 3 Then

            If Me.Join_Type = 1 Then
                JoinValue = "OR"
            ElseIf Me.Join_Type = 2 Then
                JoinValue = "AND"
            Else
                JoinValue = " "
            End If

    '--
            SearchStringTitle = "(("
            For Each varValue In SearchArray
                j = Trim(varValue)
                SearchStringTitle = SearchStringTitle & "(tbl_Studies.Study_Short_Title) Like ""*" & j & "*"""

                If varValue <> SearchArray(UBound(SearchArray)) Then
                    SearchStringTitle = SearchStringTitle & " " & JoinValue & " "
                End If
            Next varValue
            SearchStringTitle = SearchStringTitle & "))"

    '--
            SearchStringName = "(("
            For Each varValue In SearchArray
                j = Trim(varValue)
                SearchStringName = SearchStringName & "(tbl_Studies.Study_Name) Like ""*" & j & "*"""

                If varValue <> SearchArray(UBound(SearchArray)) Then
                    SearchStringName = SearchStringName & " " & JoinValue & " "
                End If
            Next varValue
            SearchStringName = SearchStringName & "))"

    '--
            SearchStringDescription = "(("
            For Each varValue In SearchArray
                j = Trim(varValue)
                SearchStringDescription = SearchStringDescription & "(tbl_Studies.Study_Description) Like ""*" & j & "*"""

                If varValue <> SearchArray(UBound(SearchArray)) Then
                    SearchStringDescription = SearchStringDescription & " " & JoinValue & " "
                End If
            Next varValue
            SearchStringDescription = SearchStringDescription & "))"

    '--
            SearchStringInvestigator = "(("
            For Each varValue In SearchArray
                j = Trim(varValue)
                SearchStringInvestigator = SearchStringInvestigator & "([qry_General:FullName_FMLD].FullName) Like ""*" & j & "*"""

                If varValue <> SearchArray(UBound(SearchArray)) Then
                    SearchStringInvestigator = SearchStringInvestigator & " " & JoinValue & " "
                End If
            Next varValue
            SearchStringInvestigator = SearchStringInvestigator & "))"

            SearchString = SearchStringTitle & " OR " & SearchStringName & " OR " & SearchStringDescription & " OR " & SearchStringInvestigator
        Else
            SearchStringTitle = "(((tbl_Studies.Study_Short_Title) Like ""*" & SearchString & "*""))"
            SearchStringName = "(((tbl_Studies.Study_Name) Like ""*" & SearchString & "*""))"
            SearchStringInvestigator = "((([qry_General:FullName_FMLD].FullName) Like ""*" & SearchString & "*""))"
            SearchStringDescription = "(((tbl_Studies.Study_Description) Like ""*" & SearchString & "*""))"

            SearchString = SearchStringTitle & " OR " & SearchStringName & " OR " & SearchStringDescription & " OR " & SearchStringInvestigator
        End If

        SearchString = SQLString & SearchString & ";"

        Me.ModifiedSearchValue.Value = SearchString
    End If
End Sub

Again, my theory is that the hanging is caused by changing the RecordSource of the subform before it has finished loading from the previous search, but I can't seem to determine any workaround.

Thanks in advance for any and all insight/help!

Answer 1

As per Olivier's suggestions, the true cause of the problem was VBA being called as part of the query [qry_General:FullName_FMLD]; switching to [qry_General:FullName_FML] (which doesn't call any VBA) eliminated all problems. I am guessing that the root of the problem was that the form was attempting to apply the filter before the query had returned a result thereby creating a corrupt filter string.

Here is the updated code using a filter method and replacing all bangs with dots:

Private Sub Search_Click()
    On Error GoTo Err_Search_Click

    Dim SearchString, SearchStringTitle, SearchStringName, SearchStringDescription, SearchStringInvestigator, JoinValue, j, SQLString As String, SearchArray, varValue As Variant

        Me.Results.Form.FilterOn = True
        SearchString = Trim(Me.SearchValue)

        If Not IsNull(SearchString) Then
            SearchArray = Split(SearchString, " ")

            If Me.Join_Type <> 3 Then

                If Me.Join_Type = 1 Then
                    JoinValue = "OR"
                ElseIf Me.Join_Type = 2 Then
                    JoinValue = "AND"
                Else
                    JoinValue = " "
                End If

        '--
                SearchStringTitle = "(("
                For Each varValue In SearchArray
                    j = Trim(varValue)
                    SearchStringTitle = SearchStringTitle & "(tbl_Studies.Study_Short_Title) Like ""*" & j & "*"""

                    If varValue <> SearchArray(UBound(SearchArray)) Then
                        SearchStringTitle = SearchStringTitle & " " & JoinValue & " "
                    End If
                Next varValue
                SearchStringTitle = SearchStringTitle & "))"

        '--
                SearchStringName = "(("
                For Each varValue In SearchArray
                    j = Trim(varValue)
                    SearchStringName = SearchStringName & "(tbl_Studies.Study_Name) Like ""*" & j & "*"""

                    If varValue <> SearchArray(UBound(SearchArray)) Then
                        SearchStringName = SearchStringName & " " & JoinValue & " "
                    End If
                Next varValue
                SearchStringName = SearchStringName & "))"

        '--
                SearchStringDescription = "(("
                For Each varValue In SearchArray
                    j = Trim(varValue)
                    SearchStringDescription = SearchStringDescription & "(tbl_Studies.Study_Description) Like ""*" & j & "*"""

                    If varValue <> SearchArray(UBound(SearchArray)) Then
                        SearchStringDescription = SearchStringDescription & " " & JoinValue & " "
                    End If
                Next varValue
                SearchStringDescription = SearchStringDescription & "))"

        '--
                SearchStringInvestigator = "(("
                For Each varValue In SearchArray
                    j = Trim(varValue)
                    SearchStringInvestigator = SearchStringInvestigator & "([qry_General:FullName_FML].FullName) Like ""*" & j & "*"""

                    If varValue <> SearchArray(UBound(SearchArray)) Then
                        SearchStringInvestigator = SearchStringInvestigator & " " & JoinValue & " "
                    End If
                Next varValue
                SearchStringInvestigator = SearchStringInvestigator & "))"

                SearchString = SearchStringTitle & " OR " & SearchStringName & " OR " & SearchStringDescription & " OR " & SearchStringInvestigator
            Else
                SearchStringTitle = "(((tbl_Studies.Study_Short_Title) Like ""*" & SearchString & "*""))"
                SearchStringName = "(((tbl_Studies.Study_Name) Like ""*" & SearchString & "*""))"
                SearchStringInvestigator = "((([qry_General:FullName_FML].FullName) Like ""*" & SearchString & "*""))"
                SearchStringDescription = "(((tbl_Studies.Study_Description) Like ""*" & SearchString & "*""))"

                SearchString = SearchStringTitle & " OR " & SearchStringName & " OR " & SearchStringDescription & " OR " & SearchStringInvestigator
            End If

            Me.Results.Form.Filter = SearchString
        End If

    Exit_Search_Click:
        Exit Sub

    Err_Search_Click:
        MsgBox ("There are no active records to review.")
        Resume Exit_Search_Click
End Sub

Again, the credit for this solution belongs to Olivier Jacot-Descombes - thanks for all your help and suggestions!