mysql递归查询树形结构，主键ID保存在一张临时表中，哪位大神帮忙看下，急。。。。。。

Question

CREATE FUNCTION getTypeChildList (rootId BIGINT)
RETURNS @service_type TABLE (type_id VARCHAR (1000))
AS
BEGIN
DECLARE sChildList VARCHAR (1000);
DECLARE sChildTemp VARCHAR (1000);
SET sChildTemp = cast(rootId AS CHAR);
WHILE sChildTemp IS NOT NULL DO
IF (sChildList IS NOT NULL) THEN
INSERT INTO @service_type VALUES (sChildTemp);
END IF;
SELECT group_concat(type_id) INTO sChildTemp FROM service_type where FIND_IN_SET(parent_id,sChildTemp)>0;
END WHILE;
RETURN;
END;

    表：CREATE TABLE `service_type` (

type_id bigint(20) NOT NULL,
type_name varchar(100) DEFAULT NULL COMMENT '类型名称',
parent_id bigint(20) DEFAULT NULL COMMENT '上一级类型id',
PRIMARY KEY (type_id)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;