Rename Parts

CREATE OR REPLACE FUNCTION evergreen.rename_part(part_id integer, new_label text)
  RETURNS void AS
$BODY$
DECLARE
    record_id bigint;
    existing_part integer;
BEGIN
    SELECT INTO record_id record FROM biblio.monograph_part WHERE id = part_id;
    IF NOT FOUND THEN
        RETURN;
    END IF;
    PERFORM * FROM biblio.monograph_part WHERE id = part_id AND label = new_label;
    IF FOUND THEN
        RETURN;
    END IF;
    SELECT INTO existing_part id FROM biblio.monograph_part WHERE label = new_label AND record = record_id;
    IF FOUND THEN
        UPDATE asset.copy_part_map SET part = existing_part WHERE part = part_id;
        UPDATE action.hold_request SET target = existing_part WHERE target = part_id AND hold_type = 'P';
        UPDATE action.aged_hold_request SET target = existing_part WHERE target = part_id AND hold_type = 'P';
        DELETE FROM biblio.monograph_part WHERE id = part_id;
    ELSE
        UPDATE biblio.monograph_part SET label = new_label, label_sortkey = NULL WHERE id = part_id;
    END IF;
END;
$BODY$
  LANGUAGE plpgsql;

CREATE OR REPLACE RULE rename_part AS
    ON UPDATE TO biblio.monograph_part
    WHERE OLD.id = NEW.id AND OLD.record = NEW.record AND OLD.label != NEW.label AND NEW.label_sortkey IS NOT NULL
    DO INSTEAD SELECT evergreen.rename_part(OLD.id, NEW.label);