create or replace function r(error_message text) returns void as $$
begin
raise notice '%', error_message;
end;
$$ language plpgsql;
select r('an error message');
NOTICE: an error message
Ответ 3
простой пример:
CREATE OR REPLACE FUNCTION test()
RETURNS TRIGGER AS
'
DECLARE
num int;
BEGIN
IF TG_OP = ''INSERT'' THEN
select count(*) into num from test_table;
IF num >= 1 THEN
RAISE WARNING ''Cannot Insert more than one row'';
RETURN OLD;
END IF;
ELSE
RETURN NEW;
END IF;
END;
' LANGUAGE plpgsql;