mysql 简单实现decode 效果

方式一

select 

IF( (SELECT COUNT(1) FROM person_punch pp WHERE pp.outer_person_id=p.id)=0,'否','是' ) as rule

from person p

方式二

select 
 IF( (SELECT COUNT(1) FROM person_punch pp WHERE pp.outer_person_id=p.id) in(0),'否','是'  ) as rule

from person p