Re: Column Specific Update Trigger Routine

On 5/6/2010 4:12 PM, Plugge, Joe R. wrote:
>
> I am trying to create a update trigger on a table that basically will
> only fire when a specific column is updated. I am using version 8.4.3.
>
> My plan of attack was to always fire on any row update, and pass in
> the OLD and NEW column that I want to check.
>
> CREATE TRIGGER check_lockout
>
> AFTER UPDATE ON acct_table
>
> FOR EACH ROW
>
> EXECUTE PROCEDURE
> acct_unlock(OLD.userid,OLD.ownerid,OLD.password,NEW.password);
>
> This fails with :
>
> [postgres(at)linux1505 ~]$ cat check_lockout_trig.sql | psql testdb
>
> ERROR: syntax error at or near "OLD"
>
> LINE 4: EXECUTE PROCEDURE
> acct_unlock(OLD.userid,OLD.ownerid,OLD.password,NEW.password);
>
> What am I doing wrong? Or is there a better way to go about this?
>
You don't call the trigger procedure with the old and new as parameters

new and old are automatically created for the function acct_unlock()

CREATE TRIGGER check_lockout

AFTER UPDATE ON acct_table

FOR EACH ROW

EXECUTE PROCEDURE acct_unlock();

Next the trigger function would look something like this

create or replace function acct_unlock()
returns trigger as
$$

if (OLD.userid <> NEW.password)
do something
end if;

$$

keep in mind the acct_unlock must be returns trigger

Then return either NEW or the OLD record
OLD if not changing the record or NEW if the updated values are to be
stored in the table.

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