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sqlserver巧用row_number和partition by分组取top数据

2024-07-18 21:05:25   211人阅读

From : http://www.jb51.net/article/29162.htm
--1.创建测试表 create table #score ( name varchar(20), subject varchar(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) --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 --4.删除临时表 truncate table #score  drop table #score
 
语法形式：ROW_NUMBER() OVER(PARTITION BY COL1 ORDER BY COL2) 
解释：根据COL1分组，在分组内部根据 COL2排序，而此函数计算的值就表示每组内部排序后的顺序编号（组内连续的唯一的)
 
结果：
 
 
 
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