private void button1_Click(object sender, EventArgs e)
{
ModelContainer usersContext = new ModelContainer();
usersContext.Database.CreateIfNotExists();
usersContext.Users.Add(new User {
Name = "Vasya"
});
usersContext.SaveChanges();
User user = usersContext.Users.First();
user.Name = "vasy" + couint;
usersContext.SaveChanges();
couint++;
}