Access VBA change Query criteria via VBA - vba

Question

I am trying to change the SQL statement of a query.
This is the following code:
Dim db As DAO.Database
Dim qdf As DAO.QueryDef
Dim sqlString As String
Set db = CurrentDb()
Set qdf = db.QueryDefs("Query1")
sqlString = "SELECT *all the Tables* FROM tab WHERE (((tab.columname)=*Variable*;"
qdf.SQL = sqlString
so my problem is the value of the Variable is not shown...
but it has to ge out of the string so I tried this:
sqlString = "SELECT *all the Tables* FROM tab WHERE (((tab.columname)= " & " *Variable*" & " ;"
I had to add "Variable" (quotation marks)
this then works half way.
it then uses the value of the variable it is set to but the quotes are missing...
The Goal of this Code is to change the Criteria that shows the data in the query.
The Variable value is as sample LA-85995561.
The way i want to change the value is via SQL statement.
I don't know further from here. thanks for any help!
(I am new to VBA)

Answer 1

Classic example to use parameterization, an industry best practice when using SQL at the application layer like VBA. And since you already use a querydef you can pass parameters easily withe PARAMETERS clause to define data type and placeholder.
SQL (save as a stored query)
PARAMETERS VariableParam Text(255);
SELECT * FROM tab WHERE tab.collumname = [VariableParam];
VBA
Dim db As DAO.Database
Dim rs As DAO.Recordset
Dim qdf As DAO.QueryDef
Dim sqlString As String
Set db = CurrentDb()
Set qdf = db.QueryDefs("mySavedQuery")
qdf!VariableParam = "LA-85995561"
Set rs = qdf.OpenRecordset()
' rs CAN BE USED IN FORMS/REPORTS RECORDSOURCES:
' Set Me.Form.Recordset = rst
' Set Me.Report.Recordset = rst

Answer 2

You could use PARAMETERS:
This passes a text string:
Sub Test()
Dim db As DAO.Database
Dim qdf As DAO.QueryDef
Dim rst As DAO.Recordset
Set db = CurrentDb
Set qdf = db.CreateQueryDef("", "PARAMETERS MyNamedSearchValue TEXT; " & _
"SELECT * FROM MyTable WHERE columname = MyNamedSearchValue")
With qdf
.Parameters("MyNamedSearchValue") = "A"
Set rst = .OpenRecordset
End With
With rst
MsgBox .Fields("MyDateField")
.Close
End With
qdf.Close
End Sub
This passes a number:
Sub Test()
Dim db As DAO.Database
Dim qdf As DAO.QueryDef
Dim rst As DAO.Recordset
Set db = CurrentDb
Set qdf = db.CreateQueryDef("", "PARAMETERS MyNamedSearchValue LONG; " & _
"SELECT * FROM MyTable WHERE columname = MyNamedSearchValue")
With qdf
.Parameters("MyNamedSearchValue") = 100
Set rst = .OpenRecordset
End With
With rst
MsgBox .Fields("MyDateField")
.Close
End With
qdf.Close
End Sub
You'll have to update the SQL to suit your needs. You could also pass it the name of a stored query rather than writing the SQL within the procedure.

Answer 3

If columname is text, then you can use something like this:
sqlString = "SELECT * FROM tab WHERE tab.columname='" & strVariable & "'"
For numeric data type:
sqlString = "SELECT * FROM tab WHERE tab.columname=" & str(lngVariable)

Answer 4

The Anser is that I had to use different marks:
WHERE (((tab.collumname)=""" & strVariable& """));"
it's about the """ & part it never made the " in the SQL thanks for all awnsers! brought me to my solution! <3