Depends on your DB design and contents.
If you mean that you have a field that just contains sequential numbers (1,2,3,etc.), then yes, you'll have to manage it all yourself.
But it's not hard.
(You can't just directily bump the numbers by one, so you make them negative at the same time you bump them and then convert all the negative numbers back.)
UPDATE tablename SET idnum = -(idnum+1) WHERE idnum >= 3
INSERT INTO tablename (idnum, other, fields) VALUE(3,'other','values')
UPDATE tablename SET idnum = -idnum WHERE idnum < 0