mysql - 无法查看全套 : Self Join - Compare where Column1 = and Column2 <>

Question

我有一个包含客户记录的表customershipments。列 Item 和 OrderNumber。我想查看一整套，其中 Item 位于多个唯一的 OrderNumber 上。

SELECT 
    distinct
    cs.item
    ,cs.ordernumber
FROM 
    customershipments cs
JOIN 
    customershipments cs2 
        ON cs.item = cs2.item
        AND cs.ordernumber <> cs2.ordernumber
WHERE
    AND cs.cdate > NOW() - INTERVAL 1 WEEK
    AND cs.isactive = 1 
    AND cs.item <>''
    AND cs.hostcompany_id =19
ORDER BY 
    cs.item, cs.ordernumber

这确实识别了我想要的items，但只返回第一个OrderNumber，而不返回第二个。除非item有两个以上的OrderNumber，否则它会向我显示所有情况。我不明白为什么。就像我说的，这足以指出我需要管理的记录(基于项目)，但它没有向我显示订单号的详尽列表。

Answer 1

您不需要自加入。只需使用聚合即可。要获取项目列表:

select item
from customershipments cs
where cs.cdate > NOW() - INTERVAL 1 WEEK and
      cs.isactive = 1 and
      cs.item <> '' and
      cs.hostcompany_id =19
group by item
having count(distinct ordernumber) > 1;

然后您可以加入此返回以获取订单列表:

select cs.*
from (select item
      from customershipments cs
      where cs.cdate > NOW() - INTERVAL 1 WEEK and
            cs.isactive = 1 and
            cs.item <> '' and
            cs.hostcompany_id =19
      group by item
      having count(distinct ordernumber) > 1
     ) i join
     customershipments cs
     on cs.item = i.item;

或者，在一行中获取订单号列表:

select item, group_concat(ordernumber)
from customershipments cs
where cs.cdate > NOW() - INTERVAL 1 WEEK and
      cs.isactive = 1 and
      cs.item <> '' and
      cs.hostcompany_id =19
group by item
having count(*) > 1;