MySQL数据库多表之间的查询

Answer 1

思路一

1. 分两种情况选出符合要求的company_id并union

2. 把这些company_id的earning求和（2013-2014）

3. 连接上company_name

好像搞的比较复杂。

with cid(id) as (
  select company_id from tableB
  where year = 2014 and earning > 20
  union
  select company_id from tableB
  where year in (2013, 2014)
  group by company_id having sum(earning) > 50
), cid_earning(id, earning) as (
  select company_id, sum(earning) from tableB
  where company_id in (select id from cid) and year in (2013, 2014)
  group by company_id
)
select a.company_name, c.earning
from cid_earning c left join tableA a using(id)

思路二

如果把2013和2014年的earning作为表的两个field，SQL的逻辑会清晰很多：

with
e3(id, earning) as (
  select company_id, earning from tableB
  where year = 2013),
  
e4(id, earning) as (
  select company_id, earning from tableB
  where year = 2014)

select a.company_name, e3.earning + e4.earning as earning
from e3 inner join e4 using(id)
        left join tableA a using(id)
where e4.earning > 20 or e3.earning + e4.earning > 50

Answer 2

好复杂哦，同问，这样的sql怎么写，我在想是不是可以写个存储过程，毕竟存储过程处理这样复杂的逻辑容易一点