generating next number... from db extraction

hi, I'm making a quoting system and need to have letters & Numbers inside the quote number. Now if I was to grab the last quote number inserted into the db and then do something like //example of $quoteID value w/out letters $quoteID = 20120250; //example of $quoteID with letters //$quoteID = abc20250; $quoteNUM = $quoteID + 1; echo $quoteNUM; it will work fine .. but the minute i add a letter to this is doesn't... now I know I can generate random numbers and letters but I need to have some order about it so the quote numbers are not all over the place... Also as an addition providing I can get this working .. I would also like to have it so that if a quote was updated the quoteID would be changed ... eg: if the quote number was abc20250 after it was updated it would be abc20250-A or something along those lines ... Cheers Peter "the only dumb question is the one that wasn't asked"