Question

我有一个带有列的SQL表：ID，ADate，XValue和Type。对于每个＆＃34; Type＆＃34;值，我想要检索最近的行（每个ADate），最近的行（每个ADate）以及包含最高行＆＃34; XValue＆＃34;的行。值。

是否可以通过单个SQL查询执行？我尝试了几次但没有成功。

Answer 1

使用row_number()你可以这样做：

select ID, ADate, XValue and Type
from (
  select *
    , min_adate  = row_number() over (partition by type order by adate asc)
    , max_adate  = row_number() over (partition by type order by adate desc)
    , max_xvalue = row_number() over (partition by type order by xvalue desc)
  from t
  ) as sub
where 1 in (min_adate,max_adate,max_xvalue)
/* --also could be written as 
where min_adate = 1
   or max_adate = 1
   or max_xvalue = 1
*/

使用common table expression可能会使其更具可读性。

;with cte as (
  select *
    , min_adate  = row_number() over (partition by type order by adate asc)
    , max_adate  = row_number() over (partition by type order by adate desc)
    , max_xvalue = row_number() over (partition by type order by xvalue desc)
  from t
)
select ID, ADate, XValue and Type
from cte
where 1 in (min_adate,max_adate,max_xvalue)

Answer 2

一种方法使用row_number()：

select t.*
from (select t.*,
             row_number() over (partition by type order by aDate desc) as seqnum_adate_desc,
             row_number() over (partition by type order by aDate asc) as seqnum_adate_asc,
             row_number() over (partition by type order by XValue desc) as seqnum_xvalue_desc
      from t
     ) t
where 1 in (seqnum_adate_desc, seqnum_adate_asc, seqnum_xvalue_desc);

Answer 3

select ID, ADate, XValue,[Type]
from (
  select *
     ,row_number() over (partition by type order by adate asc) AS DateSeq
     ,row_number() over (partition by type) AS TypeCount
     ,row_number() over (partition by type order by xvalue desc) AS ValueSeq
  from t
  ) as tt
where tt.DateSeq=1 OR tt.DateSeq=tt.TypeCount OR tt.ValueSeq=1

在同一SQL查询中选择最大值和最小值

3 个答案: