"Attempting to read while the reader is closed has no effect."

Question

I'm trying to write data from mysql uinlg c# to a .txt file but I'm getting the error "Invalid read attempt while reader is closed.".

Code here:

StreamWriter sr_Produto = new StreamWriter(@"C:\Enzo\PAP\PAP\Ficheiros\produto.txt", true);
            bdcon.Open();
            MySqlCommand cmd = new MySqlCommand("SELECT nome from produtos",bdcon);
            MySqlDataReader dr = cmd.ExecuteReader();
            if (dr.Read())
            {
                sr_Produto.Write(dr["nome"].ToString());
            }
            bdcon.Close();
            bdcon.Open();
            StreamWriter sr_Quantidade = new StreamWriter(@"C:\Enzo\PAP\PAP\Ficheiros\quantidade.txt", true);
            MySqlCommand cmd1 = new MySqlCommand("SELECT quantidade from produtos_pedidos",bdcon);
            MySqlDataReader dr1 = cmd1.ExecuteReader();
            if (dr.Read())
            {
                sr_Produto.Write(dr["quantidade"].ToString());
            }
            bdcon.Close();
            bdcon.Open();
            StreamWriter sr_Subtotal = new StreamWriter(@"C:\Enzo\PAP\PAP\Ficheiros\subtotal.txt", true);
            MySqlCommand cmd2 = new MySqlCommand("SELECT subtotal from produtos_pedidos", bdcon);
            MySqlDataReader dr2 = cmd2.ExecuteReader();
            if (dr.Read())
            {
                sr_Produto.Write(dr["subtotal"].ToString());
            }
            bdcon.Close();
            bdcon.Open();
            StreamWriter sr_Valor = new StreamWriter(@"C:\Enzo\PAP\PAP\Ficheiros\valor.txt", true);
            MySqlCommand cmd3 = new MySqlCommand("SELECT valor from produtos");
            MySqlDataReader dr3 = cmd3.ExecuteReader();
            if (dr.Read())
            {
                sr_Produto.Write(dr["valor"].ToString());
            }
            bdcon.Close();

I would be happy if anyone could help me.

Answer 1

If you look at the code, you are creating MySqlDataReader dr and loading it, then closing it and creating and loading MySqlDataReader dr1. Then you try to read the closed dr . It also looks like you may be trying to write to the wrong StreamWriter.