Update trigger, detecting missing columns

Hello all,

[Oracle 9i]

Need to detect, in a "before update for each row" trigger, if a specific column had a value informed on the SQL statement.

Example: Table ZZ with A, B, C columns

update table ZZ set C=1 where A=2; (column B wasn't informed)

update table ZZ set C=1,B=3 where A=2; (column B was informed)

Assume both sentences hit one record. (A=Primary key)

looking at :new.B doesn't help because that holds the value for B on that record.
(If the record is A=2, B=1000, C=3, then :new.B evaluates to 1000 on the first update and to 3 on the second update).

Any way to do it?
Thanks in advance
Cris Received on Tue Dec 20 2005 - 10:31:11 CST