Change WHERE clause using VBA based on form control - ms-access

Question

So, being newish to access and only using VBA in excel up until a few months ago there are quite a few commands I have absolutely 0 idea on how to use/correctly write syntax.
Problem: I have a saved query (qry_ExcelExport) which at the moment is just:
SELECT '*' FROM tbl_Contacts
What I want to do is use VBA to add/change the WHERE clause based on a user form control.
Something like:
If me.txt_Flag = "DP Delegate" then 'WHERE [DP-DEL] = True' (or = -1)
Elseif me.txt_Flag = "DP Sponsor" then 'WHERE [DP-SPON] = True' (or = -1)
And so on. (I understand that the syntax above is 100% incorrect, that's just what I'm hoping to achieve)
Using the power of the internet I managed to come across this code:
‘To change the Where clause in a saved query
Dim qdf as QueryDef
Dim db as Database
Set db = CurrentDB
Set qdf = db.QueryDefs("YourQueryName")
qdf.SQL = ReplaceWhereClause(qdf.SQL, strYourNewWhereClause)
set qdf = Nothing
set db = Nothing
Public Function ReplaceWhereClause(strSQL As Variant, strNewWHERE As Variant)
On Error GoTo Error_Handler
‘This subroutine accepts a valid SQL string and Where clause, and
‘returns the same SQL statement with the original Where clause (if any)
‘replaced by the passed in Where clause.
‘
‘INPUT:
‘ strSQL valid SQL string to change
‘OUTPUT:
‘ strNewWHERE New WHERE clause to insert into SQL statement
‘
Dim strSELECT As String, strWhere As String
Dim strOrderBy As String, strGROUPBY As String, strHAVING As String
Call ParseSQL(strSQL, strSELECT, strWhere, strOrderBy, _
strGROUPBY, strHAVING)
ReplaceWhereClause = strSELECT &""& strNewWHERE &""_
& strGROUPBY &""& strHAVING &""& strOrderBy
Exit_Procedure:
Exit Function
Error_Handler:
MsgBox (Err.Number & ": " & Err.Description)
Resume Exit_Procedure
End Function
And that first line... that very first line "To change the Where clause in a saved query" indicates that this is EXACLY what I need.
But, there is no walk-through or step-by-step beginners guide to understanding this code, the syntax or more importantly how to tie it in with a form control and it is not one I've ever used or heard of before.
EDIT: The saved query qry_ExcelExport is used in a funtion to export data
Call exportTable("qry_ExportExcel")
Where I'm calling
Public Sub exportTable(tName As String)
DoCmd.TransferSpreadsheet acExport, acSpreadsheetTypeExcel12Xml, tName, saveFileAs, True
End Sub
I need the ability to modify the where so that when I export it includes that clause as at the moment there is no WHERE clause so exports just take all the data.

Answer 1

It is normally neither needed nor practical to modify saved queries for filtering.
What you do instead is apply the filter to the form:
If me.txt_Flag = "DP Delegate" then
strFilter = "[DP-DEL] = True"
Elseif me.txt_Flag = "DP Sponsor" then
strFilter = "[DP-SPON] = True"
Else
strFilter = ""
End If
Me.Filter = strFilter
Me.FilterOn = (strFilter <> "")
Or if you need the query for something else, you can apply the filter to the query.
Set rs = DB.OpenRecordset("Select * From MySavedQuery Where " & strFilter)
Edit
If the query is used for export, it is actually one of few situations, where modifying the query is useful.
If the query is as simple as in your question, you can simply set the full SQL:
strSql = "SELECT * FROM tbl_Contacts WHERE " & strFilter
db.QueryDefs("qry_ExportExcel").SQL = strSql
Call exportTable("qry_ExportExcel")
or if the base query is more complex, use two queries: a constant one (qry_ExportExcel_Base) and a dynamic one (qry_ExportExcel)
strSql = "SELECT * FROM qry_ExportExcel_Base WHERE " & strFilter
etc. as above