I'm trying to write an SQL UPDATE but I'm not having any luck.
It looks like this:

UPDATE TAB1 JOIN TAB2 ON TAB2.FIELD = TAB1.FIELD SET TAB1.PK = TAB2.PK

I want to update TAB1.PK with TAB2.PK where TAB1.FIELD = TAB2.FIELD and there's an one to one relation between the two FIELD:s.
I don't know what I'm doin wrong but all TAB1.PK equals record no one PK in TAB2.
Any ideas???