Re: Trigger/Function - one solution - was constraint question (I think) - Mailing list pgsql-sql

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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