before update trigger:
set new.id_tezaver = (select IFNULL(id_tezaver,0) from tezaver t where term = new.term and l2='la' )
--> column id_tezaver can not be null
Yeah, I know it returns null, but should be sorted by ifnull ?
: I see it now, it actualy returns nothing, not null.
How to write trigger for that ?