Reorder / reset auto increment primary key

user_63651 0
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I have a MySQL table with an auto increment primary key. I deleted some rows in the middle of the table. Now I have, for example, something like this in the ID column: 12, 13, 14, 19, 20. I deleted the 15, 16, 17 and 18 rows.

I want to reassign / reset / reorder the primary key so that I have continuity, i.e. make the 19 a 15, the 20 a 16, and so on.

How can I do it?

mysql database
15 Answers

You could drop the primary key column and re-create it. All the ids should then be reassigned in order.

However this is probably a bad idea in most situations. If you have other tables that have foreign keys to this table then it will definitely not work.

tom_222240 
SELECT * from `user` ORDER BY `user_id`; 

SET @count = 0;

UPDATE `user`  SET `user_id` = @count:= @count + 1;

ALTER TABLE `user_id` AUTO_INCREMENT = 1;

if you want to order by

user_71297960

This works - https://stackoverflow.com/a/5437720/10219008.....but if you run into an issue 'Error Code: 1265. Data truncated for column 'id' at row 1'...Then run the following. Adding ignore on the update query.

SET @count = 0;
set sql_mode = 'STRICT_ALL_TABLES';
UPDATE IGNORE web_keyword SET id = @count := (@count+1);
user_102190080

My opinion is to create a new column called row_order. then reorder that column. I'm not accepting the changes to the primary key. As an example, if the order column is banner_position, I have done something like this, This is for deleting, updating, creating of banner position column. Call this function reorder them respectively.

public function updatePositions(){
    $offers = Offer::select('banner_position')->orderBy('banner_position')->get();
    $offersCount = Offer::max('banner_position');
    $range = range(1, $offersCount);

    $existingBannerPositions = [];
    foreach($offers as $offer){
        $existingBannerPositions[] = $offer->banner_position;
    }
    sort($existingBannerPositions);
    foreach($existingBannerPositions as $key => $position){
        $numbersLessThanPosition = range(1,$position);
        $freshNumbersLessThanPosition = array_diff($numbersLessThanPosition, $existingBannerPositions);
        if(count($freshNumbersLessThanPosition)>0) {
            $existingBannerPositions[$key] = current($freshNumbersLessThanPosition);
            Offer::where('banner_position',$position)->update(array('banner_position'=> current($freshNumbersLessThanPosition)));
        }
    }
}
user_37553690
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