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Asked: 2026-05-30T00:47:16+00:00

I am wondering if there is a way to do this through one query.

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I am wondering if there is a way to do this through one query.

Seems when I was initially populating my DB with dummy data to work with 10k records, somewhere in the mess of it all the script dummped an extra 1,044 rows where the rows are duplicates. I determined this using 

SELECT x.ID, x.firstname FROM info x
INNER JOIN (SELECT ID FROM info
GROUP BY ID HAVING count(id) > 1) d ON x.ID = d.ID

What I am trying to figure out is through this single query can I add another piece to it that will remove one of the matching dupes from each dupe found?

also I realize the ID column should have been set to auto increment, but it wasn’t

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  1. Editorial Team

    My favorite way of removing duplicates would be:

    ALTER IGNORE TABLE info ADD UNIQUE (ID);

    To explain a bit further (for reference, take a look here)

    UNIQUE – you are adding unique index to ID column.

    IGNORE – is a MySQL extension to standard SQL. It controls how ALTER TABLE works if there are duplicates on unique keys in the new table or if warnings occur when strict mode is enabled. If IGNORE is not specified, the copy is aborted and rolled back if duplicate-key errors occur. If IGNORE is specified, only the first row is used of rows with duplicates on a unique key. The other conflicting rows are deleted. Incorrect values are truncated to the closest matching acceptable value.

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