Q:

Database ID increment with deleted entries

I have entries and relationship in my database, for exemple I have a Vehicle database with relationship with drivers.  When a drive is affiliate to a vehicle it creates a session in a Vehicle history with the vehicle_id and the driver_id. 
But when I delete this vehicle let's admit it's the vehicle_id = 4 and it's the last vehicle entry, if I create an other vehicle it will automatically attribute the 4 to the new vehicle, so all the relationship between the old vehicles will now be attribute to the new one... I don't know if I make it clear enough
So do you think I have to keep the vehicle in my database even if it's deleted just to keep the ID count or do you have a particular soluce ? 
Thank you

A:

If there may ever be an opportunity for the vehicle to be used again, as opposed to deleting it, you could opt to keep the row and implement a status column.  When a user "deletes" the vehicle, you could update the status. This could also come in handy for reporting, as you aren't purging data. 
Imagine a scenario where you would like to know which drivers have changed cars this month.  As a rough example you could do:
 SELECT * FROM vehicles WHERE deleted_date BETWEEN xxx AND xxx AND vehicle_status = 'DELETED';
In your existing queries you could just select everything where the status column ! = 'DELETED'. 
The only downside to this is that you're having to store additional data, but you could implement a system to purge old records from the database after a set period of time.