查询数据表关联表中有多少条数据

A表有id,title两字段，B表有id,title,A_id三字段，A表对B表时一对多关系，A_id为A表主键。如何查询A表时同时查出B表中有多少条记录关联A表？

select a.id,a.title,count(b.id) as count from A as a LEFT JOIN B as b on a.id=b.A_id group by a.id;