SQL使用查找來返回組中的最大值？

Question

我試圖返回狀態列表中的「最大」值。但是，我想爲字符串值指定一個排序值，以便通過我自己的排名返回最大值，而不是按字母順序排列。

這裏是我的代碼：

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，這樣，而不是返回CustStatus的頂部按字母順序排列的結果，我得到了這個秩序的最先進的地位。

1. '接收的供應商'
2. '確認書SENT'
3. 'IC PENDING'
4. 'CONFIRMATION RECEIVED'
5. '已取消'

Answer 1

您使用Word 排名，但我猜你真的在問如何訂單您的查詢resul噸。如果是這樣，你可以在ORDER BY子句中使用CASE表達：

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表達式（在ELSE條件）的最後一項僅僅是爲了安全着想。

更新：根據您的後續意見，這裏是一個查詢返回的「巔峯狀態」使用ROW_NUMBER函數：

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

最好有一個表，這個狀態碼數據，並加入該表，所以將可以通過此狀態表列進行排序。