postgresql选择不同的最新记录

我有一张像这样的桌子：

id  fkey  srno  remark  date
1   A001  1
2   A001  2
3   A002  1
4   A003  1 
5   A002  2

我想要基于max srno的清晰的最新记录

2  A001  2
4  A003  1
5  A002  2

---

可以使用相关子查询

select * from tablename where srno in
(select max(srno) from tablename b where a.fkey=b.fkey)

---

使用窗口功能

行号（）

你可以用cte来写

with cte as
(
    select *,row_number() over(PARTITION by fkey order by srno desc) rn from 
    table_name t1
) select * from cte where rn=1

---

在Postgres中执行此操作的最佳方法是在上使用

DISTINCT：

SELECT DISTINCT ON (fkey) id, fkey, srno
FROM yourTable
ORDER BY fkey, srno DESC;


您可以在

操作符中使用带有

的子查询

with tab(id, fkey, srno) as 
(
 select 1,'A001',1 union all
 select 2,'A001',2 union all    
 select 3,'A002',1 union all
 select 4,'A003',1 union all    
 select 5,'A002',2   
)
select *
  from tab
 where ( fkey, srno ) in
 (
  select fkey, max(srno)
    from tab
   group by fkey
 );

id  fkey    srno
2   A001     2
4   A003     1
5   A002     2


with tab(id, fkey, srno) as 
(
 select 1,'A001',1 union all
 select 2,'A001',2 union all    
 select 3,'A002',1 union all
 select 4,'A003',1 union all    
 select 5,'A002',2   
)
select *
  from tab
 where ( fkey, srno ) in
 (
  select fkey, max(srno)
    from tab
   group by fkey
 );

id  fkey    srno
2   A001     2
4   A003     1
5   A002     2