mysql查询获取与其公司 express 相关的每个状态的计数

Question

我有两张 table

1. company_details ---- company_id、名称、地址
2. company_courier_status ---- courier_id、company_id、状态

状态列将有 0、1、2 值，其中

0 --- processing
1 --- success
2 --- returned 

如何编写 mysql 查询以获得以下输出

company_name  processing  success returned

处理列值是状态列值为 0 的计数类似地成功和返回的列

提前致谢

Answer 1

你可以像下面这样做:

SELECT
  a.name AS company_name,
  SUM(b.status = 0) AS processing,
  SUM(b.status = 1) AS success,
  SUM(b.status = 2) AS returned
FROM company_details a
LEFT JOIN company_courier_status b ON a.company_id = b.company_id
GROUP BY a.company_id, a.name