Question

SELECT id as bid,sku,product_name,
       (SELECT SUM(piece) FROM sales WHERE uid = bid) as tsa,
       (SELECT SUM(piece) FROM buying WHERE uid = bid) as taa 
FROM product WHERE ?

我想在taa - tsa if 0显示查询帮助，我需要减法

我正在使用WHERE taa-tsa = 0但是没有工作

感谢我解决了

Answer 1

试试这个：

SELECT * FROM (
    SELECT id as bid,sku,product_name,
           (SELECT SUM(piece) FROM sales WHERE uid = bid) as tsa,
           (SELECT SUM(piece) FROM buying WHERE uid = bid) as taa 
    FROM product
) as vw

WHERE (vw.taa - vw.tsa) = 0

Answer 2

如果要根据聚合值的内容过滤SELECT查询的输出，则需要在HAVING子句中指定过滤器（WHERE子句过滤输入行）。

因此：

SELECT id as bid,sku,product_name,
   (SELECT SUM(piece) FROM sales WHERE uid = bid) as tsa,
   (SELECT SUM(piece) FROM buying WHERE uid = bid) as taa 
FROM product
HAVING tsa=taa

或

SELECT ilv.*
FROM (
   SELECT id as bid,sku,product_name,
   (SELECT SUM(piece) FROM sales WHERE uid = bid) as tsa,
   (SELECT SUM(piece) FROM buying WHERE uid = bid) as taa 
   FROM product
) as ilv
WHERE tsa=taa

您的查询结构非常糟糕。如果不了解有关数据结构，数据库和查询用法的更多内容，就无法确定查询应该是什么样子。

Mysql在哪里计算

2 个答案: