查询显示行的记录数

Question

select   lsd.lsd ,count(reading.infrastructure_id),type.infrastructure_type  from public.cpreading_lsd lsd 
left join cpreading_infrastructure infra on lsd.id = infra.lsd_id  
left join public.cpreading_infrastructure_type type on type.id = infra.infrastructure_type_id
left join cpreading_cp_reading_entry reading on infra.id = reading.infrastructure_id
group by lsd.lsd,type.infrastructure_type

Answer 1

将查询设为嵌入式视图，然后从嵌入式视图中选择count（*）

例如：

select count(*) from(
select lsd.lsd 
      ,count(reading.infrastructure_id)
      ,type.infrastructure_type  
  from public.cpreading_lsd lsd 
  left join cpreading_infrastructure infra on lsd.id = infra.lsd_id  
  left join public.cpreading_infrastructure_type type on type.id = infra.infrastructure_type_id
  left join cpreading_cp_reading_entry reading on infra.id = reading.infrastructure_id
group by lsd.lsd,type.infrastructure_type
)x