mysql - MySQL Group 在 Select 上选择的行

Question

假设我有下表：

Room | Seats | Occupied
-----------------------
a1      20       10
b2      15       15
c3      45       30
d4      20       15
e5      10       10

我有一个麻烦（只是不知道如何做到这一点）生成一个 SELECT 语句，该语句将合并一些房间并总结它们的值并返回以下内容：

Room | Seats | Occupied
-----------------------
a1      20       10
b2c3d4  80       60
e5      10       10

如何才能做到这一点？

先感谢您！

Answer 1

select room,
       sum(seats) as seats,
       sum(occupied) as occupied
from your_table
group by case when room in ('b2', 'c3', 'd4') 
              then 'b2c3d4'
              else room
         end