LaravelORM 写法： ~~~ Orm::withCount['relation'])->get(); ~~~ 解析成SQL : ~~~ select `a`.*, (select count(*) from `relation` where `a`.`id` = `relation`.`aid`) as `relation_count` from `a`; ~~~ 当需要统计关联的 某个字段 sum 时，可以这样写： ~~~ Orm::withCount(['relation as relation_sum' =>function($query){ $query->select(DB::raw("sum(amount) as relationsum"); }]) ~~~ 解析成SQL: ~~~ select `a`.*, (select sum(amount) from `relation` where `a`.`id` = `relation`.`aid`) as `relation_sum_count` from `a` ; ~~~ 其他的avg ， max ， min也可以通过withCount实现