create database arron go use arron go -- createTable init Data create table students ( name varchar(25), class varchar(25), grade int ) insert into students values ('张三','语文',20) insert into students values ('张三','数学',90) insert into students values ('张三','英语',50) insert into students values ('李四',81) insert into students values ('李四',60) insert into students values ('李四',90) -- solution1 select * from students pivot( max(grade) FOR [class] IN ([语文],[数学],[英语]) ) AS pvt -- solution2 相当于自连接 select A.Name,A.grade as 语文,B.grade as 数学,C.grade as 英语 from students A,students B,students C where A.Name=B.Name and B.Name=C.Name and A.class='语文' and B.class='数学' and C.class='英语' -- solution3 select name, max(case when s.class='语文' then s.grade end) as 语文, max(case when s.class='数学' then s.grade end) as 数学, max(case when s.class='英语' then s.grade end) as 英语 from students s group by name --在有id 的情况下 create table students2 ( id int primary key identity(1,1), name varchar(25), class varchar(25), grade int ) insert into students2 values ('张三',20) insert into students2 values ('张三',90) insert into students2 values ('张三',50) insert into students2 values ('李四',81) insert into students2 values ('李四',60) insert into students2 values ('李四',90) -- 原先的solution1(有问题) select * from students2 pivot( max(grade) FOR [class] IN ([语文],[英语]) ) AS pvt -- 原先的solution2 (ok) select A.Name,students2 B,students2 C where A.Name=B.Name and B.Name=C.Name and A.class='语文' and B.class='数学' and C.class='英语' -- 原先的solution3 （ok） select name, max(case when s.class='英语' then s.grade end) as 英语 from students s group by name --unpivot 函数使用 create table test1(id int,name varchar(20),Q1 int,Q2 int,Q3 int,Q4 int) insert into test1 values(1,'a',1000,2000,4000,5000) insert into test1 values(2,'b',3000,3500,4200,5500) --实现的sql select * from test1 select id,[name],[jidu],[xiaoshou] from test1 unpivot ( xiaoshou for jidu in ([q1],[q2],[q3],[q4]) ) as f --- 以下的sql 可以替换上面的sql select id, jidu='Q1', xiaoshou=(select Q1 from test1 where id=a.id) from test1 as a union select id, jidu='Q2', xiaoshou=(select Q2 from test1 where id=a.id) from test1 as a union select id, jidu='Q3', xiaoshou=(select Q3 from test1 where id=a.id) from test1 as a union select id, jidu='Q4', xiaoshou=(select Q4 from test1 where id=a.id) from test1 as a
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