POSTGRESQL group by 取最新一条或者多条数据

需求：POSTGRESQL group by 取最新一条或者多条数据

SELECT * from

(

SELECT

t.create_time,

t.user_id,

t.seller_activity_id,

t.id,

RANK() OVER(PARTITION BY T.seller_activity_id ORDER BY T.create_time DESC) RK

FROM seller_activity_registration T

WHERE T.user_id = 'XXX'

) as A

where A.RK < 2

user_id 为用户

seller_activity_id 为业务ID，我这里是PARTITION BY T.seller_activity_id就是按这个业务分组

ORDER BY T.create_time DESC 是按创建时间排序

where A.RK < 2 和where A.RK = 1意思一样，选取记录的数量