how to select row from datagridview when cell is empty

Hi there !
how to select row from datagridview when column have cells is empty
I tried couple of this but nothing worked
Please help on this



 private void selectrow()
        {
            int i;
            for( i=0 ;i            {
                string row = dataGridView1.Rows[i].Cells["Name"].Value.ToString();
                if (row =="")
                {
                    sqlconn.Open();
                    string sqlquery = "select * from tbl... where id='" + dataGridView1.Rows[i].Cells["id"].Value.ToString() + "'";
                    SqlCommand sqlcmd = new SqlCommand(sqlquery, sqlconn);
                    SqlDataAdapter sqlda = new SqlDataAdapter(sqlcmd);
                    DataTable dt = new DataTable();
                    sqlda.Fill(dt);
                    dataGridView1.DataSource = dt;
                    sqlconn.Close();
                }
               


            }
           
        }