Question

I have an issue with getting select sub-queries to work on an UPDATE. I’m trying something like the following:

UPDATE foo
   SET bar=bar-1
 WHERE baz=
      (
       SELECT baz
       FROM foo
       WHERE fooID='1'
      )

Where foo is the table name with primary key fooID. bar and baz are of type INT. When executing this I get the following error:

Error: A query failed. You can't specify target table 'foo' for update 
in FROM clause

Answer 1

From this web article

The reason for this error is that MySQL doesn’t allow updates to a table when you are also using that same table in an inner select as your update criteria.
The article goes on to provide a solution, which is to use a temporary table.

Using this example, your update should be this:

update foo
set bar = bar - 1
where baz in
(
  select baz from
  (
    select baz
    from foo
    where fooID = '1'
  ) as arbitraryTableName
)