别名在MySQL中不起作用？别名何时生效？

Question

我想从表格中获得最大访问人数， 但出现错误Table 'test.VisitCount' doesn't exist 我相信别名VisitCount不起作用。 如何解决？

这是我的代码：

SELECT CharName, Movie, Counts
FROM 
(
    SELECT TT.Character_Name AS CharName, TT.Movie AS Movie, COUNT(*) AS Counts
    FROM TimeTable TT
    GROUP BY TT.Character_Name, TT.Movie
) AS VisitCount 
WHERE Counts = (SELECT MAX(Counts) FROM VisitCount);