题解 | #返回每个顾客不同订单的总金额#

o.表上有的列名 列名 , tb.表上没的列名 列名

from 新表 as tb, 老表 as o

where 新表.连接列 = 老表.连接列

其中新表的构成：

要select 新列名， 连接列名

from其它老表

group by 连接表名

from (
    select prod_id,
    sum(quantity) as quant_sold
    from OrderItems
    group by prod_id
) as tb1,Products as o
where o.prod_id = tb1.prod_id;