mysql - 如何使用 case 语句在 MySQL 中转换表？

Question

我正在尝试使用 case 语句在 MySQL 中转换表。这个问题在这里被问过很多次，我已经研究了所有这些答案，但我正在寻找一个解决方案:

1. 用例陈述。不是自连接、子查询或联合。
2. 只使用 SQL。不是 Excel 或 shell 脚本。
3. 适用于 MySQL。

这是表格:

create table client (
  name varchar(10),
  revenue int(11),
  expense int(11)
);

insert into client (name, revenue, expense) values ("Joe", 100, 200);
insert into client (name, revenue, expense) values ("Bill", 300, 400);
insert into client (name, revenue, expense) values ("Tim", 500, 600);

mysql> select * from client;
+------+---------+---------+
| name | revenue | expense |
+------+---------+---------+
| Joe  |     100 |     200 |
| Bill |     300 |     400 |
| Tim  |     500 |     600 |
+------+---------+---------+

我想将表格旋转成这样:

+-----+------+-----+
| Joe | Bill | Tim |
| 100 | 300  | 500 |
| 200 | 400  | 600 |
+-----+------+-----+

我怎样才能做到这一点？

我已经在 artfulsoftware dot com 和 buysql dot com 上看到了解决方案，但这些解决方案不适用于我的表。

Answer 1

see fiddle demo here

select 
sum(case when name='Joe' then revenue else 0 end) as JOE,
sum(case when name='Bill' then revenue else 0 end) as Bill,
sum(case when name='Tim' then revenue else 0 end) as TIM

from client

union

select 
sum(case when name='Joe' then expense else 0 end) as JOE,
sum(case when name='Bill' then expense else 0 end) as Bill,
sum(case when name='Tim' then expense else 0 end) as TIM

from client