一 竖表转横表
1. 首先创建竖表
create table student (
id varchar(32) primary key,
name varchar (50) not null,
subject varchar(50) not null,
result int);
2. 插入数据
insert into student (id, name, subject, result) values ('0001', '小明', '语文', 83);
insert into student (id, name, subject, result) values ('0002', '小明', '数学', 97);
insert into student (id, name, subject, result) values ('0003', '小明', '英语', 93);
insert into student (id, name, subject, result) values ('0004'', '小白', '语文', 93);
insert into student (id, name, subject, result) values ('0005', '小白', '数学', 93);
insert into student (id, name, subject, result) values ('0006', '小白', '英语', 95);
3. 查询数据
select * from student;
4. 想要将数据显示为横表, 即如下形式
废话不多说了, 直接上sql语句:
select name as '姓名',
max(case subject when '语文' then result else 0 end) '语文',
max(case subject when '数学' then result else 0 end) '数学',
max(case subject when '英语' then result else 0 end) '英语'
from student group by name;
二, 横表变竖表
1. 创建横表
create table student1 (
id varchar(32) primary key,
姓名 varchar(50) not null,
语文 int,
数学 int,
物理 int
);
2. 插入数据
insert into student1 (id, 姓名, 语文, 数学, 物理) values ('0001','小张', 93, 84, 99);
insert into student1 (id, 姓名, 语文, 数学, 物理) values ('0002','小马', 86, 92, 90);
3. 查询数据
select * from student1;
4. 将横表数据转换为竖表的形式, 即如下形式:
对应的sql语句:
select*from
(
select 姓名 as Name , '语文' as Subject , 语文 as result from student1
union all
select 姓名 as Name , '数学' as Subject , 数学 as result from student1
union all
select 姓名 as Name , '物理' as Subject , 物理 as result from student1
) t
order by name;