mysql - 如何从 MySQL 中的同一个表中减去两个计算字段？

Question

SELECT   *, 
         SUM(price+shipping+paypalfee+storefee) AS totalcost, 
         customerpaid                           AS totalrevenue, 
         (totalcost - totalrevenue)             AS profit 
FROM     tblsales 
GROUP BY orderno 
HAVING   " . $having . " 
ORDER BY $sort $order 
LIMIT    $offset,$rows

如果我省略 (totalcost - totalrevenue) as profit 查询工作正常。如何使用 totalcost 和 totalrevenue 在同一个查询中计算利润？

Answer 1

你的问题的答案是你必须重复这些表达:

select *, sum(price+shipping+paypalfee+storefee) as totalcost
       customerpaid as totalrevenue,
       (sum(price+shipping+paypalfee+storefee) - customerpaid) as profit
from tblsales
group by orderno
having " . $having . "
order by $sort $order
limit $offset, $rows;

您不能在定义列别名的同一 select 中使用列别名。

而且，您的查询看起来很奇怪。任何具有 select * 和 group by 的查询都是可疑的。您有许多列(大概)，其值将来自每个组的不确定行。一般来说，您应该明确列出列，但对于group by，您尤其应该这样做。