有一张桌子
1001 vsp,science,BBA 25-05-2020
1001 vsp,Maths,Btech 26-05-2020
1001 vsp,Maths,Btech 27-05-2020
1002 hyd,science,BBA 24-05-2020
1002 blr,Maths,Btech 25-05-2020我想要
1001 vsp,science,bba vsp,Maths,Btech vsp,Maths,Btech 发布于 2020-05-27 08:10:48
你需要一个我最喜欢的组合来实现你的目标:
https://learn.microsoft.com/en-us/sql/t-sql/queries/with-common-table-expression-transact-sql
现在解决办法是:
WITH orderedCourse AS
(
SELECT GroupId,
CourseLabel,
ROW_NUMBER() OVER (PARTITION BY GroupId ORDER BY CourseDate) AS CourseNumber
FROM @myCourses
)
SELECT TOP (1) GroupId, [1], [2], [3], [4]
FROM
(
SELECT GroupId,
CourseLabel,
CourseNumber
FROM orderedCourse
) AS src
PIVOT
(
MIN(CourseLabel) -- default agregate
FOR CourseNumber IN ([1], [2], [3], [4] /*... if you have more courses by group*/)
) AS pvt
ORDER BY GroupId其结果是:
1001 vsp,science,BBA vsp,Maths,Btech vsp,Maths,Btech NULL我使用了以下代码来声明表:
INSERT INTO @myCourses
SELECT 1001, 'vsp,science,BBA', CAST('25-05-2020' AS date) UNION ALL
SELECT 1001, 'vsp,Maths,Btech', CAST('26-05-2020' AS date) UNION ALL
SELECT 1001, 'vsp,Maths,Btech', CAST('27-05-2020' AS date) UNION ALL
SELECT 1002, 'yd,science,BBA', CAST('24-05-2020' AS date) UNION ALL
SELECT 1002, 'blr,Maths,Btech', CAST('25-05-2020' AS date);
SELECT GroupId,
CourseLabel,
CourseDate,
ROW_NUMBER() OVER (PARTITION BY GroupId ORDER BY CourseDate) AS CourseNumber
FROM @myCourses;发布于 2020-05-27 11:52:40
只需在row_number()中使用条件聚合
select col1,
max(case when seqnum = 1 then col2 end),
max(case when seqnum = 2 then col2 end),
max(case when seqnum = 3 then col2 end)
from (select t.*,
row_number() over (partition by col1 order by col3) as seqnum
from t
) t
group by col1;这与字符串聚合无关。它也不需要太多的子查询和CTE。
https://stackoverflow.com/questions/62037913
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