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

You could use the SQL Case statement, to distinguish when HEADER is null and when it has a value:
http://www.tizag.com/sqlTutorial/sqlcase.php