为什么一直说“找不到0号表”?

我正在创建一个具有添加-编辑-删除功能的系统，但每当我试图编辑我的ms SQL server 2005的值时，它一直告诉我"找不到表0"。下面是我的代码，我使用visual studio c# 2008:

private void button2_Click(object sender, EventArgs e)
    {
        try
        {
            SqlDataAdapter dad = new SqlDataAdapter();
            SqlCommandBuilder scb = new SqlCommandBuilder(dad);
            dad.UpdateCommand = new SqlCommand("UPDATE tblSchools SET Number = @id, School_Name = @school, Province = @prov, City = @city, Brgy = @brgy, Lot_Num = @lot, Area = @area, Mem_Date_Rec = @date, Cenro = @cenro", conn);
            dad.UpdateCommand.Parameters.Add("@school", SqlDbType.VarChar).Value = textBox1.Text;
            dad.UpdateCommand.Parameters.Add("@prov", SqlDbType.VarChar).Value = comboBox1.Text;
            dad.UpdateCommand.Parameters.Add("@city", SqlDbType.VarChar).Value = textBox2.Text;
            dad.UpdateCommand.Parameters.Add("@brgy", SqlDbType.VarChar).Value = textBox4.Text;
            dad.UpdateCommand.Parameters.Add("@lot", SqlDbType.NVarChar).Value = textBox5.Text;
            dad.UpdateCommand.Parameters.Add("@area", SqlDbType.Decimal).Value = textBox6.Text;
            dad.UpdateCommand.Parameters.Add("@date", SqlDbType.DateTime).Value = dateTimePicker1.Value.Date;
            dad.UpdateCommand.Parameters.Add("@cenro", SqlDbType.NVarChar).Value = textBox8.Text;
            dad.UpdateCommand.Parameters.Add("@id", SqlDbType.Int).Value = ds.Tables[0].Rows[tblNamesBS.Position][0];
            conn.Open();
            dad.UpdateCommand.ExecuteNonQuery();
            conn.Close();

        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.Message);
        }
    }

在

代码上面，我创建了一个全局函数

 DataSet ds = new DataSet();
    SqlConnection conn = new SqlConnection("Data Source=MJ-PC''SQLEXPRESS;Initial Catalog=Users;Integrated Security=True");

    BindingSource tblNamesBS = new BindingSource();

这里有什么问题?

哦，加起来，我做了一个datagridview有一个双击事件，下面是我的代码:

private void dg_DoubleClick(object sender, EventArgs e)
    {
        try
        {
            button2.Visible = true;
            button5.Visible = true;
            DataTable dt = new DataTable();
            SqlDataAdapter dad = new SqlDataAdapter("SELECT * FROM tblSchools WHERE Number ="+
                Convert.ToInt16(dg.SelectedRows[0].Cells[0].Value.ToString()) + "", conn);
            dad.Fill(dt);
            textBox1.Text = dt.Rows[0][1].ToString();
            comboBox1.Text = dt.Rows[0][2].ToString();
            textBox2.Text = dt.Rows[0][3].ToString();
            textBox4.Text = dt.Rows[0][4].ToString();
            textBox5.Text = dt.Rows[0][5].ToString();
            textBox6.Text = dt.Rows[0][6].ToString();
            //dateTimePicker1.Value = dt.Rows[0][7];
            textBox8.Text = dt.Rows[0][8].ToString();

        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.ToString());
        }
    }

这段代码会影响我的编辑吗?

DataSet ds = new DataSet();