COM serial port

I'm trying to run a code every time, where it takes the value sent by the Arduino COM port, prints it in a textbox, and then generates an insert in the mysql database.

It just read what was sent by the COM port and does not execute the insert. Help me.

 private void timer1_Tick_1(object sender, EventArgs e)
    {
        serialPort1.Open();
        string entrada = serialPort1.ReadLine();
        serialPort1.Close();
        txtIDTag.Text = entrada;

        if (txtIDTag.Text == "Gol")
        {
            string sql = "insert into tcc (Carro,Placa,Fabricante,Ano,Cor,Status,Data) value ('" + txtIDTag.Text + "','SCD - 4365','VW','2010','PRETO','NOVO', NOW())";

            comando.CommandText = sql;

            conexao.Open();

            comando.ExecuteNonQuery();

            conexao.Close();

            MessageBox.Show("Dados cadastrados com sucesso.");

            txtIDTag.Text = "";
        }}

I tried to get the IF that he executed.