sql查询到带有联合的laravel查询

Question

我想将下面的联合查询转换为laravel查询

DB::select("select lead_master.lead_stage from lead_master inner join  user_master on 
user_master.user_name=lead_master.assigned_user_name where region in (".$geo_string.") and teams 
in (".$filter_teams_string.") group by (lead_stage) union
select  meeting_hash from meetings_master where assigned_user_name in 
(".$filter_username_string.") and meeting_hash in ('follow_up','first_time') group by 
(meeting_hash) 
 union
 select sales_stage from opportunity_master where sales_stage in ('Identified','QO_to be 
 approved') and assigned_user in (".$filter_username_string.") group by (sales_stage)");

以下查询在postgre中效果很好