求助mysql查询问题

Question

我想得到：
extension_id       a（report_type=0）              b（report_type=1）
   4                                 0                                         1
   5                                 1                                         1
   6                                 2                                         0
 
求助sql语句如何写？

Answer 1

select e.extension_id,sum(e.type1) as 'a（report_type=0）',sum(e.type2) as 'b（report_type=1）'
from (select extension_id,
CASE report_type
    WHEN 0 THEN 1
    WHEN 1 THEN 0
    END AS "type1",
CASE report_type
    WHEN 1 THEN 1
    WHEN 0 THEN 0
    END AS "type2"
from extension) e
group by e.extension_id

Answer 2

select extension_id, sum(1-report_type) , sum(report_type)
from table1
group by extension_id