这篇文章通过sql示例代码给大家介绍了mysql数据库如何实现行列转换,下面话不多说,直接来看示例代码吧。
原表:
1
2
3
4
5
6
7
8
9
10
11
12
|
表名 : user
----------------------------------------
name | course | grade
----------------------------------------
zhangsan | Java | 70
----------------------------------------
zhangsan | C++ | 80
----------------------------------------
lisi | java | 90
----------------------------------------
lisi | C# | 60
----------------------------------------
|
用一条 SQL 语句得到如下形式:
1
2
3
4
5
6
7
|
----------------------------------------
name | java | C++ | C#
----------------------------------------
zhangsan | 70 | 80 | null
----------------------------------------
lisi | 90 | null | 60
----------------------------------------
|
方案一
1
2
3
4
5
|
select name ,
sum ( case when course= 'java' then grade end ) as java,
sum ( case when course= 'C++' then grade end ) as C++,
sum ( case when course= 'C#' then grade end ) as C#
from test group by name
|
方案二
1
2
3
4
5
|
select distinct c.` name ` AS name ,
( select grade from test where name = c.` name ` and course = 'java' ) as java,
( select grade from test where name = c.` name ` and course = 'C++' ) as C++,
( select grade from test where name = c.` name ` and course = 'C#' ) as C#
from test c
|
总结
以上就是这篇文章的全部内容了,希望本文的内容对大家的学习或者工作能有一定的帮助,如果有疑问大家可以留言交流。