Hi,
Create a seperate table
id_tbl
id_name varchar(20),
id_prefix char(5),
id_current_number int
Store your PK id in this table with the prefix string you want and enter by default starting number for the PK.
Then before insertion in table , generate a unique PK from id_tbl and after generating PK , increment the id_current_number in id_tbl.
You can also concatenate the julien date in string.
This is the way ,most of the companies use.
One more way is there , generating the unique string IDs from the Hexadecimals.But I don't know how to generate it. I read it somewhere.
bye
Nitin