Question

我的表格中有三列

键名，数，数据

数据包含大量重复条目。如果＆＃34; KeyName＆＃34;我需要从表中的每个重复条目中删除1行。和＆＃34;数据＆＃34;重复。我如何实现这一点是SQL查询。

Answer 1

您可以使用row_number()

为每对保留一行

with todelete as (
      select t.*,
             row_number() over (partition by keyname, data order by (select NULL)) as seqnum
      from t
     )
delete
from todelete
where seqnum > 1;

与任何此类操作一样，您应该在删除之前先检查。这很简单：

with todelete as (
      select t.*,
             row_number() over (partition by keyname, data order by (select NULL)) as seqnum
      from t
     )
select *
from todelete
where seqnum > 1;

Answer 2

这应该这样做

WITH CTE
    AS (SELECT KeyName
            , Number
            , Data
            , [rn] = ROW_NUMBER() OVER(PARTITION BY KeyName
                                          , Data ORDER BY KeyName
                                                     , Data)
        FROM   yourtable)
     /* UNCOMMENT BELOW TO DELETE */
     --DELETE
    --FROM   CTE
    --WHERE  rn > 1;

    SELECT *
    FROM   CTE
    WHERE  rn > 1;

如果两个列数据匹配，则从SQL表中删除1个重复行

2 个答案: