我怎樣才能獲得最大日期（每個主鍵）並從另一個表中獲得差異？

Question

下面我有這個樣本數據（表1）：

PKEY DATE 
---- ---- 
ABC1 2/13 
CFG5 1/05 
POK9 1/10 

，我有另一個表這些日期（表2）：

PKEY REF# DATE 
---- ---- ---- 
1  ABC1 2/14 
2  ABC1 2/20 
3  ABC1 3/01 
4  CFG5 3/05 
5  CFG5 2/10 
6  ABC1 2/25 

我想從表2得到最大日期（每REF＃）並獲得差異與從表1日期。顯示下面的結果。

REF# DIFF 
---- ---- 
POK9 55 
CFG5 54 
ABC1 21 [ *note: this is equal to datediff(day,table1.DATE,getdate()) ] 

*另外，我想使用的日期今天（與從表1日起扣除）如果樓盤編號沒有在表2現有的（像上面例子中的第3行）。希望這是有道理的..讓我知道如果有什麼不清楚，所以我可以編輯馬上..

**更新： 這是我迄今爲止嘗試..但仍然不完整..感謝辛勤工作

select t1.[REF#] 
from table1 as t1 
join table2 as t2 
on t1.[REF#] COLLATE DATABASE_DEFAULT = t2.[REF#] COLLATE DATABASE_DEFAULT 

Answer 1

SELECT t1.PKEY, CASE WHEN o.DATE IS NULL 
        THEN DATEDIFF(DAY, t1.DATE, GETDATE()) 
        ELSE DATEDIFF(DAY, t1.DATE, o.DATE) END AS DIFF 
FROM dbo.table1 t1 OUTER APPLY (
           SELECT MAX(t2.Date) AS Date 
           FROM dbo.table2 t2  
           WHERE t1.PKEY = t2.REF# 
           ) o 

演示上SQLFiddle

或不適用（）運算

SELECT t1.PKEY, (SELECT CASE WHEN MAX(o.Date) IS NULL 
          THEN DATEDIFF(DAY, t1.Date, GETDATE()) 
          ELSE DATEDIFF(DAY, t1.Date, MAX(o.Date)) END AS DIFF 
       FROM dbo.test27 o 
       WHERE t1.PKEY = o.REF# 
       ) AS DIFF        
FROM dbo.test26 t1 

查詢與您的標準

SELECT * 
FROM (
     SELECT t1.PKEY, (SELECT CASE WHEN MAX(o.Date) IS NULL 
           THEN DATEDIFF(DAY, t1.Date, GETDATE()) 
           ELSE DATEDIFF(DAY, t1.Date, MAX(o.Date)) END AS DIFF 
         FROM dbo.test27 o 
         WHERE t1.PKEY = o.REF# 
         ) AS DIFF        
     FROM dbo.test26 t1 
    ) s 
WHERE s.DIFF BETWEEN 110 AND 120 

Answer 2

WITH recorddates 
AS 
(
    SELECT PKEY, REFNo, DATE, 
      ROW_NUMBER() OVER (PARTITION BY RefNO 
           ORDER BY DATE DESC) rn 
    FROM table2 
) 
SELECT a.PKEY, 
     datediff(day,a.DATE,b.date) 
FROM table1 a 
     INNER JOIN recorddates b 
      ON a.PKey = b.RefNo 
WHERE b.rn = 1 

Answer 3

像這樣的事情？

select a.pkey 
     ,datediff(day, max(a.date), coalesce(max(b.date), getdate())) as diff 
    from table1  a 
    left join table2 b on(b.ref# = a.pkey) 
group 
    by a.pkey; 

編輯的評論： 你應該能夠過濾這樣的：

select a.pkey 
     ,datediff(day, max(a.date), coalesce(max(b.date), getdate())) as diff 
    from table1  a 
    left join table2 b on(b.ref# = a.pkey) 
group 
    by a.pkey 
having datediff(day, max(a.date), coalesce(max(b.date), getdate())) between 110 
                     and 120; 

或包裹這樣的statment：

select * 
    from (select a.pkey 
       ,datediff(day, max(a.date), coalesce(max(b.date), getdate())) as diff 
      from table1  a 
      left join table2 b on(b.ref# = a.pkey) 
     group 
      by a.pkey 
     ) 
where diff between 110 and 120;