What is wrong with my update statement with a join in Oracle?

Question

I am working with an Oracle 10g Database.

I have the following two tables:

T_DEBTOR :
    - ID_DEBTOR
    - HEADER
T_ELEMENT :
    -         


        

Answer 1

Have you tried

update
    T_ELEMENT elt
    set elt.INSURER = NVL((
        select HEADER
            from T_DEBTOR debtor
            where
                debtor.HEADER is not null
                and debtor.ID_DEBTOR = elt.ID_DEBTOR), elt.INSURER);

or something similar admittedy this is a bit unselective but I think it will do what you intend.

Answer 2

I've found a solution to solve my problem (the where clause is added):

update
    T_ELEMENT elt
    set elt.INSURER = (
        select HEADER
            from T_DEBTOR debtor
            where
                debtor.HEADER is not null
                and debtor.ID_DEBTOR = elt.ID_DEBTOR)
    where exists (
        select null
            from T_DEBTOR debtor
            where debtor.HEADER is not null
                and debtor.ID_DEBTOR = elt.ID_DEBTOR);

If you have a better solution, do not hesitate to post it!