DSpace handle returning function

DHandle.sql

-- PostgresSQL pure SQL function to return handle, given an id
-- assumes handle is uniquely in element "identifier(.uri)", uncomment non-standard uri qualifier to enforce that

CREATE OR REPLACE FUNCTION DHandle(p_id INTEGER) RETURNS text AS $$
	SELECT text_value 
		FROM metadatavalue V, metadatafieldregistry R
		WHERE R.metadata_field_id = V.metadata_field_id
		AND element ILIKE 'identifier'
		-- AND qualifier ILIKE 'uri'
		AND item_id=$1;
$$ LANGUAGE SQL;