Re: SQL function triggers

Brian Blaha wrote:
>
> I would like to write a function as a set of SQL statements, and then
> use that function
> in a trigger. However, since triggers require a return type of opaque,
> and SQL functions
> cannot return type opaque, this doesn't look possible. Am I missing
> something? The SQL
> that I would expect to do this is below. Incidentally, on an insert,
> would the trigger fire
> once, twice, or infinitely?
>
> create table test(
> a integer,
> b integer
> ) without oids;
>
> create function test_func( test.a%TYPE )
> RETURNS ?????
> AS
> 'update test set b = a where a = $1;'
> language SQL
> with (isstrict);
>
> create trigger test_trig after update
> on test for each row
> execute procedure test_func( a );

If you intend to modify the updated row only with information available
in the row itself (as in your example), a BEFORE trigger in PL/pgSQL
modifying and returning NEW should get the job done.

Jan

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