Question

如何为每个ID选择所有第n行？我的表看起来有点像这样：

    ID  fName   data
     1  Hari    20
     1  Hari    30
     2  John    89
     2  John    38
     2  John    55

在这种情况下，如何为每个ID选择所有第二行？

结果如下：

    ID  fName   data
     1  Hari    30
     2  John    38

Answer 1

这将有助于SQL SERVER 2012：

SELECT ID,  FNAME,   DATA FROM 
(
     SELECT TEST_DATA.*, 
     ROW_NUMBER() OVER (PARTITION BY ID ORDER BY ORDER_BY_CONDITION) AS RANK
     FROM TEST_DATA
) T 
WHERE T.RANK=2

按条件更改订单（相应地按ORDER_BY_CONDITION

SQL SERVER 2012的小提琴：http://sqlfiddle.com/#!6/f59a1/3

编辑：对于多个表格，您可以尝试使用CTE，如同小提琴：http://sqlfiddle.com/#!6/8a5b1d/10

Answer 2

以下查询是否适合您？（替换<tablename>和<datecolumn>名称）

SELECT tbl.*
FROM <tablename> tbl
INNER JOIN
(
    SELECT
        ID,
        ROW_NUMBER() OVER (PARTITION BY ID ORDER BY <datecolumn>) rn
    FROM <tablename>
) row_numbers
ON tbl.ID = row_numbers.ID AND tbl.<datecolumn> = row_numbers.<datecolumn> AND row_numbers.rn = 2;

<强>参考：

ROW_NUMBER function on MSDN

Answer 3

使用CTE和ROW_NUMBER() ...

;
WITH    cteData ( ID, fName, data )
          AS ( SELECT   ID ,
                        fName ,
                        data ,
                        ROW_NUMBER() 
                         OVER ( PARTITION BY ID ORDER BY DateField ) AS 'rowNum' 
FROM tblName
             )
    SELECT  ID ,
            fName ,
            data
    FROM    cteData
    WHERE   rowNum = 2--Im assuming 2 from the data presented in question

你如何为每个ID选择第n行？

3 个答案: