mysql生成三个随机数字段且总和等于100

WITH TEMP AS (
SELECT FLOOR(RAND()*5) AS AA FROM DUAL
),
TEMP1 AS (
SELECT FLOOR(RAND()*95) AS BB FROM DUAL
)
SELECT (SELECT AA FROM TEMP) AS a,(SELECT BB FROM TEMP1) AS b,100-(SELECT BB FROM TEMP1) AS c from dual