assign a datareader object value to a integer variable

i have a requirement that in my oracle database i have last record no 40.when i am inserting a new record then in my text box automatically it will show 41.how it will happen.i able to do to display 40no in textbox but i want to display 41,so how from datareader object i will get integer value so that in my logic i can increment that value in asp.net.