Re: Trigger/Function - one solution - was constraint question (I think)

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';
ENDIF; IF NEW.cr_id <> OLD.cr_id THEN   RAISE EXCEPTION 'cannot change row id'; END IF; SELECT cb_id into BAYNO from
compound_bayswhere     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
foundTHEN   RAISE EXCEPTION 'Compound / Row not found';  END IF; IF NEW.cb_id > ROWLENGTH THEN   RAISE EXCEPTION 'row
lengthexceeded: % > %',     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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