Inserting new entity into or deleting entity from database with position attribute

Question

So let's say, I got 20 entities in my database already, each of them having a position attribute to display what entity comes first on my website.

If I add a entity, I would like to actually make the position the first, so the position would be 0 at smallest as this would be my newest entity.

OR

If I remove an entity, I would like the other entities to adjust to this and fill the gap so to say.

Though there are already 20 entities in the database with positions ranging from 0-19.

All the positions can be rearranged hence the position attribute.

How would I go about this?

I know a solution by getting all the entities and iterating over them to add 1 to their position on new entity or by subtracting 1 to the position higher than the deleted one but that seems abit over the top.

Edit:

Thanks to the SQL answer, I made the answer which was:

    public function setPositions($position = 0){
        $query = $this->createQueryBuilder()
            ->update('Entity', 'e')
            ->set('e.position', 'e.position + 1')
            ->where('e.position >= :position')
            ->setParameter('position', $position)
            ->getQuery();

        $query->execute();
    }

If you put this in the Repository of your entity you can call it in your controller like:

    $this->getRepository('Entity')->setPositions();

or

    $this->getRepository('Entity')->setPositions( $entityToBeDeleted->getPosition() );

Answer 1

you can do it in one mysql query

UPDATE TABLE myTable
SET position = position + 1
WHERE position >= MyPosition

MyPosition shoul be passed as parameter from php code