Delete all rows in a table which a column has the same name repeated 2 or more times (but i don&#039-CodePudding

I would like to delete all the rows in a table where the names of a column are the same...

But I do not know the names of the values in column_1.

Always column_1 will be the one with repeats... column_2 will not. It's possible to do that? Thank you.

Example:

column_1	column_2
1	2
2	3
3	4
3	5
4	6
5	7
5	8
5	9

Expected:

column_1	column_2
1	2
2	3
4	6

CodePudding user response：

Use a subquery to help you with that:

DELETE  FROM `TableName` where column_1 in 
    (select column_1 FROM 
        (select column_1 FROM `TableName` GROUP BY `column_1` HAVING count(column_1)>1) AS t1
    )