Re: How to insert sequential number in primary row

[Phillip Ward]

I would strongly advise that you do not do this.

The Primary Key value for any record should be allocated / generated when the row is first created and should then remain unchanged until that row is finally and permanently destroyed.
Imagine the chaos if your bank "renumbered" everybody's accounts when someone [else] closed their account!

And, as Barry quite rightly says, you'd also have to change every Foreign Key value that references each and every Primary Key value that you change in this way.
That could be a massive amount of work for your database to do, for no actual benefit. I consider ON UPDATE CASCADE to be a performance killer and never use it.

Regards, Phill W.