private void btnDelete_Click(object sender, EventArgs e)
 {
     if (MessageBox.Show("Are you Sure to Delete this Record ?", "CRUD Operation", MessageBoxButtons.YesNo) == DialogResult.Yes)
     {
         using (CrudDBEntities db = new CrudDBEntities())
         {
             var entry = db.Entry(model);
             if (entry.State == EntityState.Detached)
             {
                 db.Customers.Attach(model);
             }
             db.Customers.Remove(model);
             db.SaveChanges();
             populateDataGridView();
             Clear();
             MessageBox.Show("Deleted Successfully");
         }
     }
 }
 private void btnSave_Click(object sender, EventArgs e)
 {
     model.FirstName = txtFirstname.Text.Trim();
     model.Lastname  = txtLastname.Text.Trim();
     model.City      = txtCity.Text.Trim();
     model.Address   = txtAddress.Text.Trim();
     using (CrudDBEntities db = new CrudDBEntities())
     {
         if (model.CustomerID == 0)//Insert
         {
             db.Customers.Add(model);
         }
         else //Update
         {
             db.Entry(model).State = EntityState.Modified;
         }
         db.SaveChanges();
     }
     Clear();
     populateDataGridView();
     MessageBox.Show("Submitted Successfully");
 }