SEQUENCEobject eliminates all of this. It gives you a simple way to just grab a new number and increment for the next caller. It’s very fast as there’s no visible table I/O, and it’s unaffected by rollbacks.
And it’s so much easier to use! You just ask for the next number in the sequence!
I like sequences, though the interesting thing is that 2020 me has created them a lot less frequently than 2012 me was sure I would. I’m glad they’re in the product, however.
One thing I should point out is that sequences are like identity columns in that you can have gaps due to user behavior, such as rolling back transactions. If you absolutely need gap-free sets of numbers, you’re back to Andy’s Method One, except everything has to be serializable and wrapped in explicit transactions.