chester c young wrote:
Le 20/07/09 15:19, chester c young a écrit :
within a trigger need to know if the UPDATE statement
set a column. the column might be set to the old value
or a different value.
(want to make sure the app is sending all necessary
values)
thanks
If the column to test is known -- e.g. column MyCol --,
NEW.MyCol and
OLD.MyCol -- respectively value of MyCol after UPDATE and
value of MyCol
before UPDATE -- can be compared.
for example,
create table t1( c1 int, c2 int );
insert into t1 values( 1, 2 );
1) update t1 set c1=4 where c1=1;
2) update t1 set c1=4, c2=2 where c1=1;
each update results in the same row, but in the second update c2 was actually
set.
a trigger on the update - how do we know if c2 has been actually set or not?
You cannot do that. You can only detect that a value has changed.
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