In Access Help type the following in the Answer Wizard tab
When can I update data from a query
Select that from the list for an explanation of some of the causes and
alternative solutions.
Access MVP Allen Browne has summarized the reasons:
http://allenbrowne.com/ser-61.html
Query results will be read-only if any of the following apply:
.. It has a GROUP BY clause (totals query).
.. It has a TRANSFORM clause (crosstab query).
.. It contains a DISTINCT predicate.
.. It uses First(), Sum(), Max(), Count(), etc. in the SELECT clause (performs
aggregation).
.. It involves a UNION.
.. It has a subquery in the SELECT clause.
.. It uses JOINs of different directions on multiple tables in the FROM clause.
.. The query's Recordset Type property is set to Snapshot.
.. The query is based on another query that is read-only (stacked query.)
.. Your permissions are read-only (Access security.)
.. The database is opened read-only, or the file attributes are read-only, or
the database is on read-only media (e.g. CD-ROM, network drive without write
privileges.)
--
Allen Browne - Microsoft MVP. Perth, Western Australia.
John Spencer
Access MVP 2002-2005, 2007-2008
The Hilltop Institute
University of Maryland Baltimore County