Question

------------------------------------
   X       Y
------------------------------------
   10       20
   10        5
   10        9 
   50       40
   50       30
   100      70
   100     100

将1,2,3行视为A组 B组为4,5行和6,7行作为C组

我想为一个组只获得一行，并且该行应该取决于 X，Y列值。

Y列的值最接近x

预期结果

   ------------------------------------
       X       Y
    ------------------------------------
       10        9
       50       40
       100     100

Answer 1

您可以使用条件聚合执行此操作：

select x, max(case when y <= x then y end) as y
from table t
group by x;

Answer 2

替代解决方案

DECLARE @tb TABLE (
 X float , Y float
)

INSERT INTO @tb (X,Y) values 
 (10, 20),
 (10, 5),
 (10, 9),
 (50, 40),
 (50, 30),
 (100, 70),
 (100, 100);

 select a.* from (
  select row_number() over( partition by X order by abs(X-Y) asc ) as rn, X, Y 
  from @tb
) a where a.rn = 1;

Answer 3

DECLARE @tb TABLE (
 X float , Y float
)

INSERT INTO @tb (X,Y) values 
 (10, 20),
 (10, 5),
 (10, 9),
 (50, 40),
 (50, 30),
 (100, 70),
 (100, 100);

; WITH CTE AS
 (
 Select t.X,t.Y,RN from (Select tt.X,tt.Y,ROW_NUMBER()OVER(PARTITION BY tt.X ORDER BY tt.Y DESC)RN from @tb tt )t
 )
 Select DISTINCT C.X,MAX(CASE WHEN C.Y <= C.X THEN C.Y END)AS Y FROM CTE C
 GROUP BY C.X

仅获取Y列中最接近X行的行

3 个答案: