mysql-mySql多表查询，有中间表和外键关联:mysql关联外键 select a.id,a.name,sum(case when d.STATUS=0 then 1 else 0 end) as 待处理,sum(case when d.STATUS=1 then 1 else 0 end) as 带跟进,sum(case when d.STATUS=2 then 1 else 0 end)