Question

提出了跟进问题

假设我有table1包含以下列;

示例A）

|item   |partnumber  |supplier |stock  |cost 
 CD      11A          West      11      10.11
 CD      11A          East      0       10.00
 USB     BBB          North     1       125.01
 USB     BBB          West      1       101.10

我现在所获得的（通过@Ali的帮助）是为了表1显示以下内容（基本上显示了产品最便宜的供应商）：

例B）

|item   |partnumber  |supplier   |stock |cost 
 CD      11A          East        0      10.00
 USB     BBB          West        1      101.10

This is the code for EXAMPLE B that is working:

SELECT a.name , a.partnumber , a.supplier , a.cost FROM table1 a JOIN (
SELECT name , partnumber , MIN(cost) cost
FROM table1 
GROUP BY name , partnumber ) 
b ON a.name = b.name AND a.cost = b.cost AND a.partnumber = b.partnumber

但是：如果最便宜的供应商的库存是0但另一个供应商的库存超过0，尽管价格不是最便宜的，我怎么能实现呢？以示例为例，West将取代East，如下所示：

示例C）

 |item   |partnumber |supplier  |stock  |cost 
  CD      11A          West       11     10.11
  USB     BBB          West       1      101.10

更清楚;总是向供应商展示最便宜的库存商品，除非最便宜的供应商没有库存商品而另一商品商品，在这种情况下显示相反。那么，我怎样才能实现例C）？

非常感谢！

Answer 1

您是否尝试在子查询中添加where条件？

SELECT a.name , a.partnumber , a.supplier , a.cost 
FROM table1 a 
JOIN (
    SELECT name , partnumber , MIN(cost) cost
    FROM table1 
    where stock > 0
    GROUP BY name , partnumber 
    ) b ON a.name = b.name AND a.cost = b.cost AND a.partnumber = b.partnumber

Answer 2

试试这个：

select a.item,a.partnumber,b.supplier,a.stock,min(a.cost) from
(select item,partnumber,supplier,stock,min(cost) cost from
(select * from table1) as a where stock !=0
group by item,partnumber) as  a


LEFT JOIN

(select item,partnumber,supplier,stock,cost from
(select * from table1) as a where stock !=0) as b
on a.cost = b.cost
group by a.item,a.partnumber

结果：

CD  11A West    11  10.11
USB BBB West    1   101.1

MySQL价格＆amp;股票比较

2 个答案: