由于 where 和 group by，子查询返回了超过 1 个值

Question

我想做一个简单的视图，允许查看来自不同仓库的库存总和是否 >0 并且 < 即所述产品的最低库存。

代码如下：

SELECT a.code, a.description, a.stk_min , b.Stk_Qty
FROM a 
INNER JOIN b ON a.code = b.productcode
WHERE a.stk_min > 0 and 

     (SELECT SUM(b.Stk_Qty )
     FROM b
     INNER JOIN a ON a.code = b.productcode
     Group By a.code) <= a.stk_min

当然我得到了错误

Subquery returned more than 1 value. This is not permitted when the subquery follows =, !=, <, <=, >, >= or when the subquery is used as an expression.

我可以做些什么来改变这个吗？

Answer 1

您正在查找相关子查询，而不是 group by。此查询应该可以解决问题：

SELECT a.code, a.description, a.stk_min , b.Stk_Qty
FROM a JOIN
     b
     ON a.code = b.productcode
WHERE a.stk_min > 0 and 
      (SELECT SUM(b.Stk_Qty )
       FROM b2 
       WHERE a.code = b2.productcode
      ) <= a.stk_min;

我怀疑你想要这个：

SELECT a.code, a.description, a.stk_min, SUM(b.Stk_Qty)
FROM a LEFT JOIN
     b
     ON a.code = b.productcode
WHERE a.stk_min > 0
GROUP BY a.code, a.description, a.stk_min
HAVING COALESCE(SUM(b.Stk_Qty), 0) < a.stk_min;

Answer 2

怎么样

SELECT a.code, a.description, a.stk_min, SUM(b.Stk_Qty) SumQty
FROM a join b on b.productcode = a.code 
group by a.code, a.description, a.stk_min
Where a.stk_min > 0
Having   SUM(b.Stk_Qty) <= a.stk_min

由于 where 和 group by，子查询返回了超过 1 个值

Subquery returned more than 1 value due to where and group by

sql

group-by

aggregate-functions

where