pg 分组 再进行组内排序 取组内第一个
partition by：进行分组
ORDER BY：进行排序
row_number：统计行数
select a.* from ( select *, "row_number"() over (partition by hall_id,center_frequency ORDER BY last_discover_time desc) as n from device_other where is_indoor) as a where n = 1
partition by：进行分组
ORDER BY：进行排序
row_number：统计行数
select a.* from ( select *, "row_number"() over (partition by hall_id,center_frequency ORDER BY last_discover_time desc) as n from device_other where is_indoor) as a where n = 1
