获得多个COUNT在1个查询

Question

id name type 
--------------------- 
    1  a  ir 
    2  b  sr 
    3  a  ir 
    4  a  sr 
    5  b  ir 

我想这样的使用COUNT我的输出在SQL

name ir sr 
------------- 
a  2  1 
b  1  1 

Answer 1

SELECT name, 
     SUM(CASE type WHEN 'ir' THEN 1 ELSE 0 END) AS ir, 
     SUM(CASE type WHEN 'sr' THEN 1 ELSE 0 END) AS sr 
FROM YourTable 
GROUP BY name 

在MySQL中，你可以简化这个到：

SELECT name, 
     SUM(type = 'ir') AS ir, 
     SUM(type = 'sr') AS sr 
FROM YourTable 
GROUP BY name