MAX（）WHERE - 错误

Question

我有一个选择语句（工作）

 Select * FROM 
    (SELECT id, type, color, product,  
    SUM(Quantity) AS TotalQuantity, 
    MAX(Date) AS LatestDate 
    FROM inventory 
    GROUP BY id, color, type) 
    AS alias 
    WHERE TotalQuantity > 0

我正在尝试向Max（日期）添加WHERE子句，但我没有运气：

我以为我只会将其更改为：MAX(Date) AS LatestDate WHERE stock = 1但这不起作用。

不工作：

 Select * FROM 
    (SELECT id, type, color, product,  
    SUM(Quantity) AS TotalQuantity, 
/* Problem Here */ MAX(Date) AS LatestDate WHERE stock = 1
    FROM inventory 
    GROUP BY id, color, type) 
    AS alias 
    WHERE TotalQuantity > 0

Answer 1

MAX(IF(stock = 1, Date, NULL)) AS LatestDate

如果没有这样的行，它会找到stock = 1或null的最长日期

Answer 2

使用Sub Select语句中的WHERE子句！

要获得答案，请使用此SQL：

Select * FROM 
    (SELECT id, type, color, product,  
    SUM(Quantity) AS TotalQuantity, 
    MAX(Date) AS LatestDate 
    FROM inventory 
    GROUP BY id, color, type
    WHERE TotalQuantity > 0) 
    AS alias

使用Sub Select语句中的WHERE子句！