我用下面程序用于修改数据库中的数据 ，但是却达不到效果，有高手请指导下

try
            {
                if (this.textBox1 .Text =="")
                {
                    MessageBox .Show ("请输入要修改的联系人的姓名！");
                }
                else
                {
                   string sqlconn = "Data Source=.;Initial Catalog=telephone;Integrated Security=True";
                   string sql;
                   sql =string .Format ( "select * from telephone where name='"+this.textBox1 .Text.Trim ()+"'");
                   SqlConnection conn = new SqlConnection(sqlconn);
                   SqlDataAdapter da = new SqlDataAdapter(sql,sqlconn);
                   DataSet ds = new DataSet();
                   da.Fill(ds,"telephone");
                    
                   if (ds.Tables [0].Rows.Count >0)
                   {
                       sql = string.Format(@"update telephone set mb='{3}',ph='{4}',unit='{5}',addr='{6}'where name='{1}'",this .textBox2 .Text .Trim (),
                           this.textBox3.Text.Trim(), this.textBox4.Text.Trim(), this.textBox5.Text.Trim(), this.textBox1.Text.Trim());
                       SqlConnection con = new SqlConnection(sqlconn);
                       SqlCommand cmd = new SqlCommand(sql ,con);
                       try
                       {
                           con.Open();
                           cmd.ExecuteNonQuery();
                       }
                       catch
                       { }
                       finally
                       {
                           con.Close();
                           con.Dispose();
                           cmd.Dispose();
                       }
                       MessageBox.Show("修改成功！");
                             //刷新数据
                       DataSet dss = new DataSet();
                       sql = "select * from telephone order by id";
                       SqlDataAdapter sda = new SqlDataAdapter(sql,conn);
                       da.Fill(ds,"telephone");
                       if (ds.Tables["telephone"].Rows.Count > 0)
                       {
                           this.dataGridView1.DataSource = ds.Tables["telephone"];
                       }
                   }
                }
            }
            catch
            {}