SQL，按一列分組

Question

我有這樣的數據：

 ID              VERSION        SEQUENCE 
 -------------- -------------- ---------------
  01-001         01            001          
  01-002         01            002          
  02-002         02            002

而且我只想為每個序列選擇更高的版本，以便得到這樣的結果：

 ID              VERSION        SEQUENCE 
 -------------- -------------- ---------------
  01-001         01            001             
  02-002         02            002

我認為請求應該在Sequence上包含一個group by，但是我無法使其正常運行

有人可以幫忙嗎？

Answer 1

使用通用表表達式，您可以：

with HighestSequence(ID,MaxSequence)
as 
(
   select id, max(Sequence)
   from table
   group by ID
)

select t.*
from table t
inner join HighestSequence hs
on t.id = hs.id
and t.sequence = hs.sequence

Answer 2

因此，請篩選以僅包含版本為序列最高版本的那些行

Select id, version, sequence
From DataTable dt
where version =
    (Select Max(version)
     From DataTable 
     where Sequence = dt.Sequence)

Answer 3

您沒有指定DBMS，所以這是ANSI SQL：

select id, version, sequence
from (
  select id, version, sequence,
         row_number() over (partition by id order by sequence) as rn
  from the_table
) t
where rn = 1
order by id;