无法在 postgres 中获取想要的查询

Question

假设我有下一个数据

id cid vid firstname lastname dtype dname createdat
1  32   34  ramesh    kjk       t    check 2021-11-02 10:00:51.66395
1  32   34  ramesh    kjk       t    check 2021-11-01 10:00:51.66395
1  32   4   raj       kjk       c    check 2021-11-04 10:00:51.66395

除外 o/p:

id cid vid firstname lastname dtype dname createdat
1  32   34  ramesh    kjk       t    check 2021-11-02 10:00:51.66395
1  32   4   raj       kjk       c    check 2021-11-04 10:00:51.66395

只需要获取每个用户的唯一一条最新记录(vid)，文档类型可以是c或t

Answer 1

使用相关子查询

  select t1.* from table_nam t1
    where t1.createdat=(select max(createdat) from table_nam t2 where t1.vid=t2.vid)

你也可以使用 distinct on

select distinct on (vid) as vid,createdat,cid
from table_name
order by vid,createdat desc