Re: Trigger/Function - one solution - was constraint question (I think) - Mailing list pgsql-sql
From | Rafael Domiciano |
---|---|
Subject | Re: Trigger/Function - one solution - was constraint question (I think) |
Date | |
Msg-id | 3a0028490812041159u39698b7dy51a3097d25c22c01@mail.gmail.com Whole thread Raw |
In response to | Re: Trigger/Function - one solution - was constraint question (I think) (Gary Stainburn <gary.stainburn@ringways.co.uk>) |
List | pgsql-sql |
I would develop like this (No so many changes, it is basically a small trigger)
create or replace function compound_rows_range_check() returns trigger as
$body$
DECLARE
BAYNO int4;
BEGIN
-- First Verification = if changing compound or row fail
IF (old.co_id <> new.co_id or
old.cr_id <> new.cr_id) THEN
RAISE EXCEPTION 'Cannot change co_id () | cr_id ()', old.co_id, old.cr_id;
END IF;
-- Last Verification
SELECT cb_id into BAYNO from compound_bays
where
co_id = NEW.co_id and
cr_id = NEW.cr_id and
cb_id > NEW.cr_length
order by cb_id desc
limit 1;
IF (FOUND) THEN
RAISE EXCEPTION 'Cannot remove occupied bays: % > %', BAYNO, NEW.cr_length;
END IF;
RETURN NEW;
END;
$body$
LANGUAGE 'plpgsql';
2008/12/4 Gary Stainburn <gary.stainburn@ringways.co.uk>
I have managed to develop one solution using functions and triggers. Has
anyone got a better solution?
Gary
create unique index "compound_bays_unique_index" on compound_bays using btree
(co_id,cr_id,cb_id);
create or replace function compound_rows_range_check() returns trigger as
$proc$
DECLARE
BAYNO int4;
BEGIN
-- if changing compound or row fail
IF NEW.co_id <> OLD.co_id THEN
RAISE EXCEPTION 'cannot change compound id';
END IF;
IF NEW.cr_id <> OLD.cr_id THEN
RAISE EXCEPTION 'cannot change row id';
END IF;
SELECT cb_id into BAYNO from compound_bays where
co_id = NEW.co_id and
cr_id = NEW.cr_id and
cb_id > NEW.cr_length
order by cb_id desc
limit 1;
IF found THEN
RAISE EXCEPTION 'Cannot remove occupied bays: % > %',
BAYNO, NEW.cr_length;
END IF;
RETURN NEW;
END;
$proc$ LANGUAGE plpgsql;
CREATE TRIGGER compound_rows_range_check BEFORE UPDATE on compound_rows
FOR EACH ROW EXECUTE PROCEDURE compound_rows_range_check();
create or replace function compound_bays_range_check() returns trigger as
$proc$
DECLARE
ROWLENGTH int4;
BEGIN
SELECT cr_length into ROWLENGTH from compound_rows where
co_id = NEW.co_id and
cr_id = NEW.cr_id;
IF not found THEN
RAISE EXCEPTION 'Compound / Row not found';
END IF;
IF NEW.cb_id > ROWLENGTH THEN
RAISE EXCEPTION 'row length exceeded: % > %',
NEW.cb_id,ROWLENGTH;
END IF;
RETURN NEW;
END;
$proc$ LANGUAGE plpgsql;
CREATE TRIGGER compound_bays_range_check BEFORE INSERT OR UPDATE on
compound_bays
FOR EACH ROW EXECUTE PROCEDURE compound_bays_range_check();
--
Gary Stainburn
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