数据库实现行列转换(mysql示例)

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：

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：

----------------------------------------
name   | java | c++ | c#
----------------------------------------
zhangsan | 70  | 80  | null
----------------------------------------
lisi   | 90  | null | 60
----------------------------------------

方案一

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

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

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