SQL為每個ID選擇最新記錄

Question

我有兩個表，第一個是這樣的：

     INTERNSHIP
ID|  Term
---------
1 | 2015
1 | 2014
2 | 2016
2 | 2017

第二個是這樣的：

       Term
Term| Term Description | End Date
---------------------------------
2014 |  Summer 2014   | 8/12014
2014 |  Summer 2014   | 8/12014
2015 |  Fall 2015     | 12/1/2015
2017 |  Spring 2017   | 4/1/2017
2017 |  Spring 2017   | 6/1/2017

我需要找到所有ID的最新術語的“術語描述”。 期望的結果是這樣的：

ID| Term | Term Description 
------------------
1 |  2015   |  Fall 2015   
2 |  2017   |  Spring 2017

我做了一些研究，並提出了這樣的解決方案：

SELECT INTERNSHIP.ID, INTERNSHIP.Term
FROM INTERNSHIP
WHERE (
  SELECT MAX(INTERNSHIP.Term)
  )
GROUP BY INTERNSHIP.ID

這樣，我就獲得了帶有最新術語的唯一ID，但是我無法將其與術語描述結合在一起。 有人可以幫助我獲得理想的結果嗎？

Answer 1

您的SQL版本是否允許您使用窗口函數？

如果是這樣，您可以像這樣輕松解決：

SELECT C.ID,C.Term,C.Term_Description
FROM(
SELECT A.ID,A.TERM,B.Term_Description,Max(A.Term) OVER (PARTITION BY A.ID) AS Most_Recent_Year
FROM INTERNSHIP A INNER JOIN TERM B ON A.Term = B.Term
)C
WHERE C.Term = C.Most_Recent_Year

Answer 2

嘗試這個：

SELECT i.id, i.term, t.Term_Description
FROM INTERNSHIP i
INNER JOIN Term t ON t.Term = i.term
INNER JOIN (
            SELECT MAX(t.End_Date) End_Date
            FROM INTERNSHIP i
            INNER JOIN Term t ON t.Term = i.term
            GROUP BY i.ID) t1 ON t1.End_Date = t.End_Date

Answer 3

我建議：

SELECT i.id, i.term, t.Term_Description
FROM (SELECT i.id, MAX(i.Term) as term
      FROM INTERNSHIP i
      GROUP BY i.id
     ) i JOIN
     Term t
     ON t.Term = i.term;