Mysql SELECT inde i OPDATERING

Consp har ret i, at det ikke er understøttet. Der er dog en løsning:

UPDATE forms SET
pos = (SELECT MIN(pos)-1 FROM (SELECT * FROM forms) AS x)
WHERE id=$id

En version, der sandsynligvis er hurtigere:

UPDATE forms 
SET pos = (SELECT pos-1 FROM (SELECT MIN(pos) AS pos FROM forms) AS x)
where id=$id