how to increment the waitlist id for the next student

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C#

Student login as follows

Student id 1000
Password 12345

Waitlist screen as follows

course name AFF
Batch date 23 Mar 2015
submit (Button)

When i click the submit button in gridview record as follows

Waitlistid Coursename Batch date
1 AFF 23 Mar 2015


Suppose when second student login as follows

Student id 2000
Password 23241

Waitlist screen as follows

course name MFA
Batch date 20 June 2015
submit (Button)

When i click the submit button in gridview record as follows

Waitlistid Coursename Batch date
2 MFA 20 June 2015

when second student login( student id (2000)) in gridview i want to generate the waitlistid 2.

for that how can i do in asp.net using c#.