SQL使用查找来返回组中的最大值？

Question

我试图返回状态列表中的“最大”值。但是，我想为字符串值指定一个排序值，以便通过我自己的排名返回最大值，而不是按字母顺序排列。

这里是我的代码：

select x.wbs1, x.wbs2, x.wbs3, x.custstatus 
    from (
      select wbs1,wbs2,wbs3,custstatus=MAX(custstatus) 
      from Projects_CRStatus 
      where custsentdate >= 'June 1, 2001' AND custsentdate <= 'June 30, 2013' 
      AND CustStatus IN ('RECEIVED AT VENDOR', 'CONFIRMATION SENT', 
      'IC PENDING','CONFIRMATION RECEIVED','CANCELLED') 
      group by wbs1,wbs2,wbs3) x 
    inner join (
      select wbs1,wbs2,wbs3,custsentdate=max(custsentdate) 
      from Projects_CRStatus 
      group by wbs1,wbs2,wbs3) y 
    on (x.wbs1=y.wbs1 and x.wbs2=y.wbs2 and x.wbs3=y.wbs3) 

    ORDER BY CustEnrollmentID 

我想要做的是排名CustStatus的值，这样，而不是返回CustStatus的顶部按字母顺序排列的结果，我得到了这个秩序的最先进的地位。

1. '接收的供应商'
2. '确认书SENT'
3. 'IC PENDING'
4. 'CONFIRMATION RECEIVED'
5. '已取消'

Answer 1

您使用Word 排名，但我猜你真的在问如何订单您的查询resul吨。如果是这样，你可以在ORDER BY子句中使用CASE表达：

ORDER BY CASE WHEN CustStatus = 'RECEIVED AT VENDOR' then 1 
       WHEN CustStatus = 'CONFIRMATION SENT' then 2 
       WHEN CustStatus = 'IC PENDING' then 3 
       WHEN CustStatus = 'CONFIRMATION RECEIVED' then 4 
       WHEN CustStatus = 'CANCELLED' then 5 
       ELSE 6 
     END, CustEnrollmentID 

CASE表达式（在ELSE条件）的最后一项仅仅是为了安全着想。

更新：根据您的后续意见，这里是一个查询返回的“巅峰状态”使用ROW_NUMBER函数：

select wbs1, wbs2, wbs3, custstatus 

from (
    select x.wbs1, x.wbs2, x.wbs3, x.custstatus, 
     ROW_NUMBER() OVER(PARTITION BY x.wbs1, x.wbs2, x.wbs3 
         ORDER BY CASE 
         WHEN x.CustStatus = 'RECEIVED AT VENDOR' then 1 
         WHEN x.CustStatus = 'CONFIRMATION SENT' then 2 
         WHEN x.CustStatus = 'IC PENDING' then 3 
         WHEN x.CustStatus = 'CONFIRMATION RECEIVED' then 4 
         WHEN x.CustStatus = 'CANCELLED' then 5 
         ELSE 6 END) as rn 
    from (
     select wbs1,wbs2,wbs3,custstatus=MAX(custstatus) 
     from Projects_CRStatus 
     where custsentdate >= 'June 1, 2001' 
     AND custsentdate <= 'June 30, 2013' 
     AND CustStatus IN ('RECEIVED AT VENDOR', 'CONFIRMATION SENT' 
      ,'IC PENDING','CONFIRMATION RECEIVED','CANCELLED') 
     group by wbs1,wbs2,wbs3) x 
    inner join (
     select wbs1,wbs2,wbs3,custsentdate=max(custsentdate) 
     from Projects_CRStatus 
     group by wbs1,wbs2,wbs3) y 
    on (x.wbs1=y.wbs1 and x.wbs2=y.wbs2 and x.wbs3=y.wbs3) 
    ) z 

WHERE RN = 1 

Answer 2

最好有一个表，这个状态码数据，并加入该表，所以将可以通过此状态表列进行排序。