Oracle用function生成UUID方法

CREATE OR REPLACE FUNCTION get_uuid
RETURN VARCHAR
IS
guid VARCHAR (50);
BEGIN
guid := lower(RAWTOHEX(sys_guid()));
RETURN
substr(guid,1,8)||'-'||substr(guid,9,4)||'-'||substr(guid,13,4)||'-'||substr(guid,17,4)||'-'||substr(guid,21,12);
END get_uuid;