I have created a small test for updating table using Linq-to-SQL DataContext as follows:

using (pessimistic_exampleDataContext db = new pessimistic_exampleDataContext())
{
   var query = db.test1s.First(t => t.a == 3);

   if (query.b == "a")
      query.b = "b";
   else
      query.b = "a";

   db.SubmitChanges();
}

But after executing this code in a console application in Main method, when I select records from the table, the record is not updated.

I have debugged through the code, and it is not even throwing any exception.

What can be the problem ?