Partition分组使用和行列转换

CREATE TABLE score
(
name NVARCHAR(20),
subject NVARCHAR(20),
score INT
)
--2.插入测试数据
INSERT INTO score(name,subject,score) VALUES('张三','语文',98)
INSERT INTO score(name,subject,score) VALUES('张三','数学',80)
INSERT INTO score(name,subject,score) VALUES('张三','英语',90)
INSERT INTO score(name,subject,score) VALUES('李四','语文',88)
INSERT INTO score(name,subject,score) VALUES('李四','数学',86)
INSERT INTO score(name,subject,score) VALUES('李四','英语',88)
INSERT INTO score(name,subject,score) VALUES('李明','语文',60)
INSERT INTO score(name,subject,score) VALUES('李明','数学',86)
INSERT INTO score(name,subject,score) VALUES('李明','英语',88)
INSERT INTO score(name,subject,score) VALUES('林风','语文',74)
INSERT INTO score(name,subject,score) VALUES('林风','数学',99)
INSERT INTO score(name,subject,score) VALUES('林风','英语',59)
INSERT INTO score(name,subject,score) VALUES('严明','英语',96)

select * from score

select subject from score   for xml path('')
SELECT Subject+','  FROM score
    where name='林风'
  FOR XML PATH('')
 
   SELECT  cast(score as varchar)+',' FROM score
    where name='林风'
  FOR XML PATH('')
 
SELECT name ,sum(score),
(SELECT Subject+',' FROM score
  WHERE name=A.name
  FOR XML PATH('')) AS StuList,
 
 
  (SELECT cast(score as varchar(10))+',' FROM score
  WHERE name=A.name
  FOR XML PATH('')) AS StuList
 
 
FROM score A
GROUP BY name

--3.取每个学科的前3名数据

SELECT * FROM
(
SELECT subject,name,score,ROW_NUMBER() OVER(PARTITION BY subject ORDER BY score DESC) AS num FROM score
) T WHERE T.num <= 3 ORDER BY subject
--------------------------------------
SELECT * FROM
(
SELECT subject,name,score,Rank() OVER(PARTITION BY subject ORDER BY score DESC) AS num FROM score
) T WHERE T.num <= 3 ORDER BY subject
-----------------------------------------------

SELECT * FROM
(
SELECT subject,name,score,Dense_Rank() OVER(PARTITION BY subject ORDER BY score DESC) AS num FROM score
) T WHERE T.num <= 3 ORDER BY subject
-----------------------------------------------
/*以下是我对4个排名函数的类比表格：         
               排名连续性   排名并列性         
RANK()        不一定连续    有并列         
DENSE_RANK()   连续         有并列         
ROW_NUMBER()   连续         无并列         
NTILE()        连续         有并列         
*/

--4行转列

SELECT name,ISNULL([数学],0) [数学],ISNULL([英语],0) [英语],ISNULL([语文],0) [语文]
FROM score PIVOT (max(score) FOR subject IN ([数学],[英语],[语文]) ) AS pt

SELECT name,ISNULL([数学],0) [数学],ISNULL([英语],0) [英语]
FROM score PIVOT (max(score) FOR subject IN ([数学],[英语]) ) AS pt


SELECT Name AS 姓名 ,
     MAX(CASE Subject WHEN '数学' THEN score ELSE 0 END) [数学] ,
     MAX(CASE Subject WHEN '英语' THEN score ELSE 0 END) [英语] ,
     MAX(CASE Subject WHEN '语文'  THEN score ELSE 0 END) [语文]
   FROM score GROUP BY name

--5动态行转列
declare @sql varchar(8000)
--set @sql = 'select Name as ' + '姓名'
set @sql=''
select @sql = @sql+ ' , max(case Subject when ''' + Subject + ''' then score else 0 end) [' + Subject + ']'
from (select distinct Subject from score) as a
--set @sql = @sql + ' from score group by name'
print @sql
exec(@sql)

--6 动态Pivot
declare @sql varchar(500)
declare @sql2 varchar(500)
select @sql2=  isnull(@sql2 + ',' , '') + 'isnull(['+Subject+'],0) as '+Subject+'' from score group by Subject
select @sql = isnull(@sql + ',' , '') + '['+Subject+']' from score group by Subject
print @sql
print @sql2
exec ('select Name,'+@sql2+' from (
select Name,s.Score,Subject from score s
 
) a pivot (sum(Score) for Subject in (' + @sql + ')) b')

   
SELECT name,sum(score) score,
(SELECT Subject+',' FROM score
  WHERE name=A.name
  FOR XML PATH('')) AS StuList,
  (SELECT cast(score as varchar(10))+',' FROM score
  WHERE name=A.name
  FOR XML PATH('')) AS StuList
FROM score A
GROUP BY name

 

--7 XML PATH
   select b.name,b.score,
   LEFT(b.StuList,LEN(b.StuList)-1) StuList,
   LEFT(b.ScoreList,LEN(b.ScoreList)-1) ScoreList
    from (
    SELECT name,sum(score) score,
(SELECT Subject+',' FROM score
  WHERE name=A.name
  FOR XML PATH('')) AS StuList,
  (SELECT cast(score as varchar(10))+',' FROM score
  WHERE name=A.name
  FOR XML PATH('')) AS ScoreList
FROM score A
GROUP BY name ) b  order by score desc