从每组重复项中选择一行

Question

模拟表格

我需要从第一个表中删除重复记录。如果我们有重复的address_num，例如100，我们将使用AddressType＆＃34; Home＆＃34;行。

请注意，address_num不包含3个或更多的副本;它们要么在表格中出现一次，要么两次。例如，address_num 200出现一次。因此，我们只是按原样抓住它。

ID列是主键。

具有正确复选标记的第二个表是结果表。如何编写打印出第二个表的oracle SQL查询？

Answer 1

您可以使用row_number()并智能使用order by：

来执行此操作

select t.*
from (select t.*,
             row_number() over (partition by address_num
                                order by (case when AddressType = 'Home' then 1 else 0 end) desc
                               ) as seqnum
      from table t
     ) t
where seqnum = 1;

Answer 2

类似的东西：

SELECT id, address_num, ...
FROM (
    SELECT id, address_num, ...
         , row_number() over (partition by address_num
                              order by addresstype) as rn
    FROM T
) AS X
WHERE rn = 1

Answer 3

仅选择每组Dupes中ID最低的行。

 Select * From MockUpTable m
 Where Id = 
     (Select Min(id)
      From MockUpTable
      Where address_num = m.address_num)