string qry2 = "Select * from student";
           SqlCommand cmd2 = new SqlCommand(qry2, sconn);
           SqlDataAdapter da2 = new SqlDataAdapter(cmd2);
           DataTable dt2 = new DataTable();
           da2.Fill(dt2);
           BindingSource bs2 = new BindingSource();
           bs2.DataSource = dt2;
           dataGridView2.DataSource = bs2;
           DataGridViewCheckBoxColumn colCB = new DataGridViewCheckBoxColumn();
           colCB.HeaderText = "Delete";
           colCB.ValueType = typeof(System.Boolean);
           colCB.TrueValue = "True";
           colCB.FalseValue = "False";
           dataGridView2.AutoGenerateColumns = false;
           dataGridView2.Columns.Insert(0, colCB);

           dataGridView2.Columns[0].Width = 40;