Sql command executed more then once!!!i dont want that...

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C

.NET

Visual-Studio

Im developing a windows mobile app and i have a form where i add a barcode from the textbox to the database.but i want that the text in the text box stays there.the insert statement becomes valuable when enter is pressed!everything goes well,except that the text inside the box is being inserted more then once until the next barcode.

here is the code:

if (e.KeyChar == (char)13)
            {

                _connection.Open();

                SqlCeCommand desc_command = new SqlCeCommand("select description from Items where barcode=@barcode;", _connection);
                desc_command.Parameters.AddWithValue("@barcode", txt_barcode.Text);
                SqlCeDataReader rdr = desc_command.ExecuteReader();
                if (rdr.Read())
                {
                    txt_description.Text = rdr.GetString(0);
                    SqlCeCommand _addcommand = new SqlCeCommand("insert into Inventory values(@barcode,@amount);", _connection);
                    _addcommand.Parameters.AddWithValue("@barcode", txt_barcode.Text);
                    _addcommand.Parameters.AddWithValue("@amount", txt_amount.Text);
                    _addcommand.ExecuteNonQuery();                                      
                    _connection.Close();
                    txt_barcode.SelectAll();                   
                }

                else
                {
                     PlaySound(@"\Windows\Voicbeep", IntPtr.Zero, (int)(PlaySoundFlags.SND_FILENAME | PlaySoundFlags.SND_SYNC));
                    txt_description.Text = "--------------";
                    txt_barcode.SelectAll();
                    txt_barcode.Focus();

                    _connection.Close();
                }

               
              }