Re: Column manipulation with triggers

In article <6vas1b$drk$1@News.Dal.Ca>, garagan@cs.dal.ca (Sean Garagan) wrote: > Good day, Hello, > > I am trying to write a trigger that updates a column by subtracting the > values of the old and new tables. I cannot find a way to get the subtract > operator to act on the column values unfortunately. It looks something like > the following: > > create trigger audit_table_trig> update of B on table > referencing old as pre > new as post > for each row( > insert into audit_table > values ( post.B, > post.B - pre.B ));> I think the problem is an expression in values ( ) part of insert. Of course you can save just post.B and pre.B and calculate differense later. Or if trigger-based calculation is just necessary, I will suggest to create audit_table with one more column to save post.B, pre.B and column for difference and create trigger 'insert on audit_table' to update difference column of inserted row. It will work if you will use in your trigger insert into audit_table (col1, col2) values ( post.B, pre.B )); to resolve trigger reentrancy problem. > I have done something along these lines in Oracle, which allows you to use > PL/SQL in a trigger statement, but it doesn't seem to work this way with > Informix. > > Any help will be appreciated, > Sean > HTH -- Vardan Aroustamian -----------== Posted via Deja News, The Discussion Network ==---------- http://www.dejanews.com/ Search, Read, Discuss, or Start Your Own