Access can figure out what the parameter is when the query is run in the
grid. Then Access will inform the Jet Engine what it is.
However, when the same query is run in code, you must tell the Jet engine
what the
parameter is yourself.
This is the slickest way to do it:
With queries that contain parameters that are all references to
controls on open forms, you can simulate the expression service that Access
provides when the queries are run through the user interface, as follows:
Set db = CurrentDb
Set qdf = db.QueryDefs("MyQuery")
For Each prm In qdf.Parameters
prm.Value = Eval(prm.Name)
Next prm
Set rs = qdf.OpenRecordset(dbOpenDynaset)
' or qdf.Execute dbFailOnError