mysql先去重再按条件汇总_MySql实现根据某个条件去重求和

//第一图直接查询出所有的id

SELECT

d.id

FROM

t_device d

LEFT JOINt_device_collect_state a on d.id = a.device_collect_id

LEFT JOIN t_group b on d.group_id = b.id

LEFT JOIN t_farm c on d.farm_id = c.id

where

d.del_flag = '0' and d.type =2 and c.id =1

order by b.create_time desc

//第二图 查询所有id(已经去重)

SELECT

distinct d.id

FROM

t_device d

LEFT JOINt_device_collect_state a on d.id = a.device_collect_id

LEFT JOIN t_group b on d.group_id = b.id

LEFT JOIN t_farm c on d.farm_id = c.id

where

d.del_flag = '0' and d.type =2 and c.id =1

order by b.create_time desc

//第三图 求和(去重求和)

SELECT

count(distinct d.id)

FROM

t_device d

LEFT JOINt_device_collect_state a on d.id = a.device_collect_id

LEFT JOIN t_group b on d.group_id = b.id

LEFT JOIN t_farm c on d.farm_id = c.id

where

d.del_flag = '0' and d.type =2 and c.id =1

order by b.create_time desc