mysql 保存两个变量相除结果，并同时要显示这两个变量？

SELECT 1 as qq , 2 as ww , qq/ww as percent;

错误提示：
[SQL]

SELECT 1 as qq , 2 as ww , qq/ww as percent;
[Err] 1054 - Unknown column 'qq' in 'field list'

正确该如何写？

SELECT
t1.qq,
t2.ww,
t1.qq / t2.ww AS percent
FROM
(SELECT 1 AS qq) t1,
(SELECT 2 AS ww) t2

SELECT 1 as qq , 2 as ww , 1/2 as percent;

SET @qq = 1;
SET @ww = 2;
SELECT @qq as qq , @ww as ww, @qq/@ww as percent;

SELECT
t1.qq,
t2.ww,
t1.qq / t2.ww AS percent
FROM
(SELECT 1 AS qq) t1,
(SELECT 2 AS ww) t2
这个正解

SELECT 1 as qq , 2 as ww , 1/2 as percent;

SELECT 1 as qq , 2 as ww , 1/2 as percent; 是对的

SELECT 1 as qq , 2 as ww , 1/2 as percent; 是对的，真的可行