Oracle SQL從有序數據集中獲取第一個和最後一個記錄

Question

我正在使用的軟件要求獲取有序數據集的第一個和最後一個記錄。數據集按日期列排序。

I中的數據有：

--table "notes": 
-- ordered by this 
--    | 
--    V 
note_id  date_created attribute1 attribute2 ... -- I want to get 
----------------------------------------------------- 
596   2014/01/20 ...   ...   ... -- <- this 
468   2014/02/28 ...   ...   ... 
324   2014/03/01 ...   ...   ... 
532   2014/04/08 ...   ...   ... 
465   2014/05/31 ...   ...   ... -- <- and this 

所需的輸出：

596   2014/01/20 ...   ...   ... 
465   2014/05/31 ...   ...   ... 

Answer 1

您可以使用窗口函數：

select t.* 
from (select t.*, row_number() over (order by date_created) as seqnum, 
      count(*) over() as cnt 
     from t 
    ) t 
where seqnum = 1 or seqnum = cnt; 

在Oracle 12，你也可以這樣做：

select t.* 
from t 
order by date_created 
fetch first 1 rows only 
union all 
select t.* 
from t 
order by date_created desc 
fetch first 1 rows only; 

Answer 2

如果我說得對，試試這個：

select t1.* 
    from YOUR_TABLE t1 
    , (
     select min(note_id) keep(dense_rank first order by date_created) min_val 
      , max(note_id) keep(dense_rank last order by date_created) max_val 
      from YOUR_TABLE 
     ) t2 
where t1.note_id = t2.min_val 
    or t1.note_id = t2.max_val