Save changes to the bank

Question

I am trying to change the data saved in the Database, basically when I double click on DataGrid he populates my TextBoxs to make the changes in the bank, but when I click to save it from the following error. Detail this error only happens when I add one more value to the txtPreco, if I delete what was inserted and put another value it registers a new product (which is not supposed to happen when I edit)

here the photo from the database

this is my code I’m using to try to change the data registered in the database

  //criando a bool
        bool informacoesSalvas = false;

        private void btnSalvar_Click(object sender, EventArgs e)
        {

        if (string.IsNullOrWhiteSpace(txtNome.Text))
        {
            System.Windows.Forms.MessageBox.Show("O nome do produto está vazio, por favor digite algo");
            return; // sai do método
        }
        else if (string.IsNullOrWhiteSpace(txtPreco.Text))
        {
            System.Windows.Forms.MessageBox.Show("O Preço do produto está vazio, por favor digite algo");
            return;
        }

        else if (informacoesSalvas)
        {

            // Abre a conexão
            conectar.Open();

            //Query SQL
            MySqlCommand command = new MySqlCommand("INSERT INTO Produto (Nome,Descricao,Preco)" +
            "VALUES('" + txtNome + "','" + txtDescricao.Text + "','" + txtPreco.Text + "' )", conectar);

            //Executa a Query SQL
            command.ExecuteNonQuery();

            // Fecha a conexão
            conectar.Close();

            //Mensagem de Sucesso
            MessageBox.Show("Alterado com Sucesso!", "Informação", MessageBoxButtons.OK, MessageBoxIcon.Information);

            informacoesSalvas = true;
        }
        else
        {
            conectar.Open();
            //Convertendo

            Converter = Convert.ToDecimal(txtPreco.Text);

            //MessageBox.Show("Conectado");

            MySqlCommand Inserir = new MySqlCommand();
            Inserir.Connection = conectar;
            Inserir.CommandText = "INSERT INTO Produto (Nome, Descricao, Preco, `status`) VALUES (@peca, @nome, @quantidade, @dataentrada)";

            Inserir.Parameters.AddWithValue("@peca", txtNome.Text);
            Inserir.Parameters.AddWithValue("@nome", txtDescricao.Text);
            Inserir.Parameters.AddWithValue("@quantidade", txtPreco.Text);
            Inserir.Parameters.AddWithValue("@dataentrada", ckbAtiv.Checked);

            Inserir.ExecuteNonQuery();
            conectar.Close();
            MessageBox.Show("Produto Cadastrado", "Concluido",
              MessageBoxButtons.OK,
              MessageBoxIcon.Information);
            selecionarCategoria();
        }
    }

Answer 1

Using a fragment of your example to show the use of Begintransaction and Commit.

note: I copied exactly the same content of the question.

    conectar.Open();

    //inicia a transação de dados
    var transaction = conectar.BeginTransaction();


    MySqlCommand command = new MySqlCommand("INSERT INTO Produto (Nome,Descricao,Preco)" +
    "VALUES('" + txtNome + "','" + txtDescricao.Text + "','" + txtPreco.Text + "' )", conectar);

    //insere os dados.
    command.ExecuteNonQuery();

    // Fecha a transação de dados salvando as alterações efetuadas
    transaction.Commit();


    conectar.Close();

Answer 2

Good people that was how I managed to solve this problem, now already this changing in the bank

 private void dataGridView1_CellClick(object sender, DataGridViewCellEventArgs e)
    {
        lblID.Text = dataGridView1.CurrentRow.Cells[0].Value.ToString();
        txtNome.Text = dataGridView1.CurrentRow.Cells[1].Value.ToString();
        txtDescricao.Text = dataGridView1.CurrentRow.Cells[2].Value.ToString();
        txtPreco.Text = dataGridView1.CurrentRow.Cells[3].Value.ToString();
        alterar = Convert.ToInt32(dataGridView1.CurrentRow.Cells[0].Value.ToString());


        Converter = Convert.ToDecimal(txtPreco.Text);

    }

    private void btnSalvar2_Click(object sender, EventArgs e)
    {
        MySqlConnection conectar = new MySqlConnection("server=127.0.0.1;database=ProdPacote; Uid=root; pwd=1234;");
        conectar.Open();
        var transaction = conectar.BeginTransaction();
        if (alterar <= 0)
        {
            MySqlCommand Inserir = new MySqlCommand();
            Inserir.Connection = conectar;
            Inserir.CommandText = "INSERT INTO Produto (Nome, Descricao, Preco, `status`) VALUES (@Nome, @Descricao, @Preco, @status)";

            Inserir.Parameters.AddWithValue("@Nome", txtNome.Text);
            Inserir.Parameters.AddWithValue("@Descricao", txtDescricao.Text);
            Inserir.Parameters.AddWithValue("@Preco", txtPreco.Text);
            Inserir.Parameters.AddWithValue("@status", ativIndat);
            Inserir.ExecuteNonQuery();

            transaction.Commit();
            conectar.Close();
            MessageBox.Show("Produto cadastrado", "Concluido",
            MessageBoxButtons.OK,
            MessageBoxIcon.Information);
            selecionarCategoria();

        }
        else
        {
            conectar.Close();
            conectar.Open();
            //Convertendo

            Converter = Convert.ToDecimal(txtPreco.Text);

            //MessageBox.Show("Conectado");

            MySqlCommand Inserir = new MySqlCommand();
            Inserir.Connection = conectar;
            Inserir.CommandText = "UPDATE  Produto SET Nome = '"+txtNome.Text+"', Descricao = '"+txtDescricao.Text+"', Preco ="+Converter+", status = "+ativIndat +" WHERE ID_Produto ="+alterar+" ";


            Inserir.ExecuteNonQuery();
            conectar.Close();
            alterar = 0;
            txtNome.Text = "";
            txtPreco.Text = "";
            txtDescricao.Text = "";
            MessageBox.Show("Produto alterado", "Concluido",
              MessageBoxButtons.OK,
              MessageBoxIcon.Information);
            selecionarCategoria();


        }