Re: INSERT or UPDATE TRIGGER

This is what I have come up with. Comments are welcomed.

CREATE OR REPLACE FUNCTION hll_pg_fn_ident_insert()
RETURNS TRIGGER AS $pg_fn$
-- ROW AFTER TRIGGER
-- trigger passes identifier_type, _value and _description
-- received as ARGV[0], ARGV[1] and ARGV[2]
BEGIN
INSERT INTO identifiers(
entity_id,
identifier_type,
identifier_value,
identifier_description)
VALUES(
NEW.id,
TG_ARGV[0],
TG.ARGV[1],
TG_ARGV[2]);

-- Assume the INSERT fails because of a unique key violation,
-- (entity_id + identifier_type + identifier_value)
--
-- This does not matter since we only need ensure that this
-- alias exists, so handle the exception and return:

EXCEPTION
WHEN unique_violation THEN
-- do nothing
NULL;
END;
$pg_fn$ LANGUAGE plpgsql;

COMMENT ON FUNCTION hll_pg_fn_ident_insert IS
'Used by entities trigger. Inserts a corresponding
identifiers row.'

CREATE TRIGGER hll_pg_tr_entity_identifier_akna
AFTER INSERT OR UPDATE ON entities
FOR EACH ROW EXECUTE PROCEDURE hll_pg_fn_identifier_insert(
"AKNA", entities.entity_common_name, "Common Name
auto-insert");

COMMENT ON TRIGGER hll_pg_tr_entity_identifier_akna IS
'Inserts an alias identifier for common name if one does not
exist'

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