Allow the use of tables in update queries without requiring them to be writeable
When executing an update query with multiple tables, all tables are currently required to be writeable.
Please allow us to use read-only tables and queries as a source of data for update queries, e.g.
UPDATE MyWritableTable rw
INNER JOIN MyReadOnlyTable ro ON ro.ID = rw.ID
SET rw.Field1 = ro.Field1
Since there are no write actions to MyReadOnlyTable, this query should not require it to be writable, but it does.
The current behaviour is a common source of misunderstanding (I often see questions about it on Stack Overflow), and limits the ability to update/merge in data from read-only data sources.
