加入集合

Question

我在面试中遇到了这样的问题。输出将包含具有最高标记的每个ID最高年龄。

Answer 1

使用ROW_NUMBER()与PARTITION BY如下，让您的输出

;WITH T AS 
(
    SELECT 
     ID, 
     Age, 
     Marks, 
     ROW_NUMBER() OVER(PARTITION BY ID ORDER BY Age DESC,MArks DESC) AS PartNo 
    FROM @tbl1 
) 
SELECT 
    T.ID, 
    T2.Name, 
    T.Age, 
    T.Marks 
FROM T 
LEFT JOIN @tbl2 T2 ON T.ID=T2.ID 
WHERE PartNo=1 

Answer 2

SELECT A.ID,A.Name,MA.MaxAge Age,MM.MaxMarks Marks FROM tbl2 A 
LEFT JOIN (SELECT Id, Max(Age)MaxAge FROM tbl1 GROUP BY ID) MA ON MA.ID = a.ID 
LEFT JOIN (SELECT Id, Max(Marks)MaxMarks FROM tbl1 GROUP BY ID) MM ON MM.ID = a.ID 

使用此查询，你会得到你的结果