Delete all Duplicate Rows except for One in MySQL?

Question

Delete all Duplicate Rows except for One in MySQL?

How would I remove all duplicate data from a MySQL Table?

For example, with the following data:

SELECT * FROM names;



+----+--------+

| id | name   |

+----+--------+

| 1  | google |

| 2  | yahoo  |

| 3  | msn    |

| 4  | google |

| 5  | google |

| 6  | yahoo  |

+----+--------+

I would practiceSELECT DISTINCT name FROM names; if it were a SELECT query.

How would I do this with DELETE to only remove duplicates and keep just one record of each?

duplicate sql mysql

3 years ago by Amit8z4mc

2 Answers

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**espadacoder11** · Answer 1 · 2021-06-08T12:19:22

If you want to keep the row with the lowest id value:



DELETE FROM NAMES

 WHERE id NOT IN (SELECT  

                    FROM (SELECT MIN(n.id)

                            FROM NAMES n

                        GROUP BY n.name) x)

If you want the id value that is the highest:



DELETE FROM NAMES

 WHERE id NOT IN (SELECT  

                    FROM (SELECT MAX(n.id)

                            FROM NAMES n

                        GROUP BY n.name) x)

The subquery in a subquery is necessary for MySQL, or you'll get a 1093 error.

**RoliMishra** · Answer 2 · 2021-06-09T12:20:22

If you want to keep the row with the lowest id value:

DELETE n1 FROM names n1, names n2 WHERE n1.id > n2.id AND n1.name = n2.name

If you want to keep the row with the highest id value:

DELETE n1 FROM names n1, names n2 WHERE n1.id < n2.id AND n1.name = n2.name

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Delete all Duplicate Rows except for One in MySQL?

2 Answers

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