ROW_NUMBER() OVER函数运用

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语法：ROW_NUMBER() OVER(PARTITION BY COLUMN ORDER BY COLUMN)

PARTITION BY:相当于数据库中的group by

说明：row_number() OVER (PARTITION BY COL1 ORDER BY COL2) 表示根据COL1分组，在分组内部根据 COL2排序，而此函数计算的值表示每组排序后的顺序编号（从1开始，组内连续的唯一的编号)

--新建表Table_A

create table Table_A(name varchar(8),Subject varchar(8),Grade int)
insert into Table_A values(‘小A‘,‘数学‘,90)
insert into Table_A values(‘小A‘,‘语文‘,79)
insert into Table_A values(‘小A‘,‘英语‘,88)
insert into Table_A values(‘小B‘,‘数学‘,99)
insert into Table_A values(‘小B‘,‘语文‘,76)
insert into Table_A values(‘小B‘,‘英语‘,82)
insert into Table_A values(‘小C‘,‘数学‘,78)
insert into Table_A values(‘小C‘,‘语文‘,67)
insert into Table_A values(‘小C‘,‘英语‘,81)
insert into Table_A values(‘小D‘,‘数学‘,93)
insert into Table_A values(‘小D‘,‘语文‘,75)
insert into Table_A values(‘小D‘,‘英语‘,84)

--原始表

select * from Table_A

--执行以下语句后

select ROW_NUMBER() OVER(PARTITION BY name order by Grade desc) as id,name,Subject,Grade from Table_A

--根据字段name分组，Grade排序

--提取成绩中的最大值，可用以下语句

select * from
(
    select ROW_NUMBER() OVER(PARTITION BY name order by Grade desc) as id,name,Subject,Grade from Table_A
)TT where id = 1

--每名学生，只显示前2单成绩，修改代码为以下即可

select * from
(
    select ROW_NUMBER() OVER(PARTITION BY name order by Grade desc) as id,name,Subject,Grade from Table_A
)TT where id between 1 and 2

ROW_NUMBER() OVER函数运用

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原文地址：http://www.cnblogs.com/hbwy/p/4914155.html