Autogenerate Primary Key

Hi all
How do you autogenerate your own primary key in SQL.
Instead of SQL generating an IDENTIY number which would be 1, 2 ,3..etc
I was wanting to give it my own sequence of numbers, how exactly do I do that can anyone help??why? what do these sequence of numbers look like? do they have special meanings?|||Humour me for a second - why?|||why? what do these sequence of numbers look like? do they have special meanings?Humour him too ^^^^^^^ :)|||The number would look like this 07-0000

The first two digits are the year, the others are in numerical secquence.. like 07-0001, 07-0002, 07-0003 (JP IR#)and so on, they normally log this in a journal but now they want a database to log this in where the database would generate these numbers and they have to do is put in the type, the amount and whether its a hold or not. its for our surveillance department and they have IR numbers that help in their reports|||smart numbers are stupid for many many reasons. I would just store those 2 parts in seperate fields and bring them together in the UI so they can see the number they want.|||Sorry I didnt realize they would be stupid, I just thought I would ask. Doesnt hurt to ask. I wasnt sure how to create something like|||Heh. The problem with semi intelligent (and also dumb) bespoke keys is when it comes to serialisation. This is not much of an issue if you add one row at a tme and do not have high concurrency but if either of these are not true then performance really suffers. Do you need to reset the count each year? SQL Server does not support this internally. I think other RDBMSs (like MySQL) do but that is not much help :)