mysql - sql max 函数错误 : Incorrect syntax near the keyword 'select'

Question

我有下一个 sql 代码，您可以在下面看到。除了带有 where 条件的最后一行，它都可以工作。

    select m.model,m.price from (
    select product.model, pc.price
    from product
    join pc 
    on product.model=pc.model
    union
    select product.model, laptop.price
    from product
    join laptop 
    on product.model=laptop.model
union
    select product.model, printer.price
    from product
    join printer 
    on product.model=printer.model
    ) m
    where m.price = select max(m.price) from m

我有下一个错误:关键字“select”附近的语法不正确。如果我把最后一行写成:where m.price = m.price 它也可以工作

Answer 1

您是否按型号追求最高价格？

select m.model,MAX(m.price) as price from 
(
    select product.model, pc.price
    from product
    join pc 
    on product.model=pc.model
    union
    select product.model, laptop.price
    from product
    join laptop 
    on product.model=laptop.model
union
    select product.model, printer.price
    from product
    join printer 
    on product.model=printer.model
    ) m
GROUP BY m.model