Question

Currently I have a database that is not managed by me and I can’t do any changes to it, the id field is a smallint 2 unsigned that gives you up to 65535 id entries.

My problem is that I need to reuse the ids because of the above limitations, how could I get the next usable ID in order or what would you do to manage the inserts with the above limitations ?

Answer 1

Check if 1 is free. If not:

SELECT MIN(a.id) + 1 AS smallestAvailableId
FROM your_table AS a
LEFT JOIN your_table AS a2
        ON a2.id = a.id + 1
WHERE a2.id IS NULL