如何删除sql server中的重复行？ [英] How to delete duplicate rows in sql server?

问题描述

如何删除不存在唯一行ID的重复行？

How can I delete duplicate rows where no unique row id exists?

我的表是

col1  col2 col3 col4 col5 col6 col7
john  1    1    1    1    1    1 
john  1    1    1    1    1    1
sally 2    2    2    2    2    2
sally 2    2    2    2    2    2

我想在重复删除后留下以下内容：

I want to be left with the following after the duplicate removal:

john  1    1    1    1    1    1
sally 2    2    2    2    2    2

我已经尝试了几个查询，但我认为它们依赖于行ID，因为我没有得到所需的结果。例如：

I've tried a few queries but i think they depend on a row id as I don't get desired result. For example:

DELETE FROM table WHERE col1 IN (
    SELECT id FROM table GROUP BY id HAVING ( COUNT(col1) > 1 )
)

推荐答案

像CTEs和 ROW_NUMBER 两个组合允许我们查看哪些行被删除（或更新），因此只需更改 DELETE FROM CTE ... 到 SELECT * FROM CTE ：

I like CTEs and ROW_NUMBER as the two combined allow us to see which rows are deleted (or updated), therefore just change the DELETE FROM CTE... to SELECT * FROM CTE:

WITH CTE AS(
   SELECT [col1], [col2], [col3], [col4], [col5], [col6], [col7],
       RN = ROW_NUMBER()OVER(PARTITION BY col1 ORDER BY col1)
   FROM dbo.Table1
)
DELETE FROM CTE WHERE RN > 1

演示 （结果不同，我认为这是由于您的错字）

DEMO (result is different; I assume that it's due to a typo on your part)

COL1    COL2    COL3    COL4    COL5    COL6    COL7
john    1        1       1       1       1       1
sally   2        2       2       2       2       2

此示例由 col1 单列确定重复$ c> PARTITION BY col1 。如果要包含多个列，只需将它们添加到 PARTITION BY 中：

This example determines duplicates by a single column col1 because of the PARTITION BY col1. If you want to include multiple columns simply add them to the PARTITION BY:

ROW_NUMBER()OVER(PARTITION BY Col1, Col2, ... ORDER BY OrderColumn)

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