C# error Concurrency violation: the UpdateCommand affected 0 of the expected 1

private void button2_Click(object sender, EventArgs e)
        {
            string connectionString;
            
            connectionString = "Server=localhost;User Id=root; Password=1234; Database=db2; Pooling=false;CharSet=tis620;";
            connection = new MySqlConnection(connectionString);
            MySqlCommand cmd = new MySqlCommand("Select * from data Where Id = '"+comp.Text.Trim()+"'",connection);
            sda.SelectCommand = cmd;
            dt = new DataTable();
            sda.Fill(dt);
            Table1.DataSource = dt;
            
        }
private void button3_Click(object sender, EventArgs e)
        {
            
            
            cmdbl = new MySqlCommandBuilder(sda);

            sda.Update(dt);//Error!!!!
            MessageBox.Show("Save data complete");
            
        }