吨-SQL查询分组

Question

。 只有两个值的“X”和“Y”。所以表看起来像

Name  OnGoing 
---------------- 
A  X 
A  X 
A  X 
B  Y 
B  Y 
C  X 
C  X 
C  X 

如何编写这样的查询，可以交替每组名称的值。

Answer 1

如何像

DECLARE @Table TABLE(
     Name VARCHAR(10) 
) 

INSERT INTO @Table SELECT 'A' 
INSERT INTO @Table SELECT 'A' 
INSERT INTO @Table SELECT 'A' 
INSERT INTO @Table SELECT 'B' 
INSERT INTO @Table SELECT 'B' 
INSERT INTO @Table SELECT 'C' 
INSERT INTO @Table SELECT 'C' 
INSERT INTO @Table SELECT 'C' 

SELECT *, 
     CASE 
      WHEN RowNum % 2 = 0 
       THEN 'Y' 
      ELSE 'X' 
     END 
FROM @Table t INNER JOIN 
     (
      SELECT Name, 
        ROW_NUMBER() OVER (ORDER BY Name) RowNum 
      FROM @Table 
      GROUP BY Name 
     ) sub ON t.Name = sub.Name 

Answer 2

改变你的表以包括新列：

ALTER TABLE YourTable ADD 
    OnGoing char(1) NULL 
GO 

，然后试试这个：

DECLARE @YourTable table (Name char(1), OnGoing char(1)) 
INSERT @YourTable Values ('A',NULL) 
INSERT @YourTable Values ('A',NULL) 
INSERT @YourTable Values ('A',NULL) 
INSERT @YourTable Values ('B',NULL) 
INSERT @YourTable Values ('B',NULL) 
INSERT @YourTable Values ('C',NULL) 
INSERT @YourTable Values ('C',NULL) 
INSERT @YourTable Values ('C',NULL) 


;WITH TableRows AS 
(
SELECT 
    *, ROW_NUMBER() OVER(ORDER BY Name) AS RowID 
    FROM (SELECT DISTINCT 
       * 
       FROM @YourTable 
     ) dt 
) 
UPDATE y 
    SET OnGoing=CASE 
        WHEN r.RowID % 2 = 1 THEN 'X' 
        ELSE 'Y' 
       END 
    FROM @YourTable   y 
     INNER JOIN TableRows r ON y.Name=r.Name 

SELECT * FROM @YourTable 

OUTPUT：

Name OnGoing 
---- ------- 
A X 
A X 
A X 
B Y 
B Y 
C X 
C X 
C X 

(8 row(s) affected) 

Answer 3

这将这样的伎俩：

select 
    t1.Name, 
    sub1.OnGoing 
from 
    TableOne t1 
    INNER JOIN 
(select 
    Name, 
    CASE RANK() over (order by Name) % 2 
    WHEN 0 THEN 'Y' 
    WHEN 1 THEN 'X' 
    END as OnGoing 
from 
    TableOne 
group by Name) sub1 ON sub1.Name = t1.Name 

这是我测试的实际输出：

Name OnGoing 
---- ------- 
A X 
A X 
A X 
B Y 
B Y 
C X 
C X 
C X