Issue in Auto Generate Number in VB.Net

Question

Hi Sunny,

           Now only i got issue in Auto generate number as we Discussed yesterday. The problem is it is working fine but if first time i have inserted "ABC12300001" no. in database and i ll close application then again i ll run application and insert data relate to ABC and 123 that time again it is taking "ABC12300001".

           But it should not happen means repeatition should not be there,  I just want to ask you that should i run sql query and check whether that particular auto number exist or not or how i should avoid this problem.

I am waiting for reply.