I know it's a confusing title, but the example will show what I want to achieve:
UPDATE tr.tbl_to_be_updated SET cat=-1 WHERE cat NOT IN (SELECT c.id
FROM tr.cat as c WHERE c.sh=tbl_to_be_updated.sh))
How can I achieve this? With this query I receive an error that it's not allowed.
UPDATE tbl_to_be_updated
LEFT JOIN cat ON cat.sh = tbl_to_be_updated.sh
SET tbl_to_be_updated.cat = -1
WHERE cat.sh IS NULL