I have a trigger that, if it can't find a match, inserts a new record in TableA with all the data from the new record in tableB.
If it finds a match it should update field a,b,c,d,e... with :new.a, :new.b, :new.c, :new.d, :new.e...
but only if the new a,b,c,d,e... are not null.
SET...