Why is my query read-only?

If you cannot edit the data in a query, this list may help you identify why it is not updatable:

It has a GROUP BY clause. A Totals query is always read-only.
It has a TRANSFORM clause. A Crosstab query is always read-only.
It uses First(), Sum(), Max(), Count(), etc. in the SELECT clause. Queries that aggregate records are read-only.
It contains a DISTINCT predicate. Set Unique Values to No in the query's Properties.
It involves a UNION. Union queries are always read-only.
It has a subquery in the SELECT clause. Uncheck the Show box under your subquery, or use a domain aggregation function instead.
It uses JOINs of different directions on multiple tables in the FROM clause. Remove some tables.
The fields in a JOIN are not indexed correctly: there is no primary key or unique index on the JOINed fields.
The query's Recordset Type property is Snapshot. Set Recordset Type to "Dynaset" in the query's Properties.
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.)
The query calls a VBA function, but the database is not in a trusted location so the code cannot run. (See the yellow box at the top of this Access 2007 page.)
The fields that the query outputs are Calcluated fields (Access 2010.)