Separate COM object from adjacent RCW

Question

In this Try-catch occurs the following error message:

The code:

        try
        {
            dbConnection.Open();

            cmdQry.CommandText = "SELECT * FROM tbl_ItensEmbaOrdem WHERE idOrdem=?";

            cmdQry.Parameters.Clear();
            cmdQry.Parameters.Add(new OleDbParameter("@id", Convert.ToInt32(cbCodigo.Text)));

            OleDbDataReader RD = cmdQry.ExecuteReader();
            while(RD.Read())
            {
                ListViewItem item = new ListViewItem(RD["nomeEmba"].ToString());
                item.SubItems.Add(RD["unEmba"].ToString());
                item.SubItems.Add(RD["qtEmba"].ToString());
                item.SubItems.Add(RD["loteEmba"].ToString());

                lvEmba.Items.Add(item);
            }
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.Message + "\nCódigo PRO05X137", "Erro", MessageBoxButtons.OK, MessageBoxIcon.Error);
        }
        finally
        {
            dbConnection.Close();
        }

This mistake has already happened to me, but I do not remember how I solved, besides I researched about this object COM and its RCW and I found nothing. I would like to know the cause of the error and what are these two objects. Grateful.

P.S: error occurs only at the point OleDbDataReader RD = cmdQry.ExecuteReader(); and ONLY at this point of the code.

EDIT

The complete code:

private void cbCodigo_SelectedIndexChanged(object sender, EventArgs e)
    {
        string strConnection = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source="
               + Application.StartupPath + @"\dbProjetoLagune1.mdb";

        OleDbConnection dbConnection = new OleDbConnection(strConnection);

        OleDbCommand cmdQry = dbConnection.CreateCommand();

CODE NOT NEEDED HERE IN THE MIDDLE

        try
        {
            dbConnection.Open();

            cmdQry.CommandText = "SELECT * FROM tbl_ItensEmbaOrdem WHERE idOrdem=?";

            cmdQry.Parameters.Clear();
            cmdQry.Parameters.Add(new OleDbParameter("@id", Convert.ToInt32(cbCodigo.Text)));

            OleDbDataReader RD = cmdQry.ExecuteReader();
            while(RD.Read())
            {
                ListViewItem item = new ListViewItem(RD["nomeEmba"].ToString());
                item.SubItems.Add(RD["unEmba"].ToString());
                item.SubItems.Add(RD["qtEmba"].ToString());
                item.SubItems.Add(RD["loteEmba"].ToString());

                lvEmba.Items.Add(item);
            }
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.Message + "\nCódigo PRO05X137", "Erro", MessageBoxButtons.OK, MessageBoxIcon.Error);
        }
        finally
        {
            dbConnection.Close();
        }
    }

End of the code where the error is.

Answer 1

You created and opened your connection, but when creating the OleDbCommand you are not associating it to your open connection, that is, this command refers to what connection? I made a code snippet for you to see the change that should be made. I added using to ensure that the Dispose be called at the end of the use of resources.

using (OleDbConnection dbConnection = new OleDbConnection(connectionString))
{
    dbConnection.Open();

    using (OleDbCommand command = dbConnection.CreateCommand())
    {
        command.CommandText = "SELECT * FROM tbl_ItensEmbaOrdem WHERE idOrdem = @idOrdem";

        command.Parameters.AddRange(new OleDbParameter[]
        {
            new OleDbParameter("@idOrdem",  Convert.ToInt32(cbCodigo.Text))
        });

        OleDbDataReader reader = command.ExecuteReader();

        while (reader.Read())
        {
            ListViewItem item = new ListViewItem(RD["nomeEmba"].ToString());
            item.SubItems.Add(RD["unEmba"].ToString());
            item.SubItems.Add(RD["qtEmba"].ToString());
            item.SubItems.Add(RD["loteEmba"].ToString());

            lvEmba.Items.Add(item);
        }

        reader.Close();
    }
}

Answer 2

I found the problem:

I simply needed to close the OleDbDataReader that was in another part of the code with the method Close().

I thank those who have invested time in the issue.