Question

I’m having some trouble figuring out why I can only get the children of one parent in my treeview to be added. I’m sure it’s something simple I’m forgetting, but I’m a bit stumped. I put **’s around the loop I’m having trouble with but included the rest of the code in case there’s something wrong there.

Code:

string connStr = @"Provider=Microsoft.ACE.OLEDB.12.0; Data Source=PartsTree.accdb"; //2007 db format
            //string connStr = @"Provider=Microsoft.JET.OLEDB.4.0; Data Source=PartsTree.accdb"; //2003 db format
            try
            {
                using (OleDbConnection dbConn = new OleDbConnection(connStr))
                {
                    string queryString = "SELECT ID, parent_ID, description FROM Parts;"; //Note two semicolons
                    dbConn.Open();

                    OleDbCommand dbCmd = dbConn.CreateCommand();
                    dbCmd.CommandText = queryString;
                    OleDbDataReader rdr = dbCmd.ExecuteReader();

                    int numberColumns = rdr.FieldCount; // How many columns are there in the DB
                    for (int x = 0; x < numberColumns; x++)
                    {
                        treeView1.Nodes.Add(rdr.GetName(x)); // Add a parent node to the tree for each column
                    }


                    **for (int y = 0; y <= numberColumns; y++)
                    {
                        while (rdr.Read())
                        {
                            string childData = rdr[y].ToString();
                            treeView1.Nodes[y].Nodes.Add(childData);
                        }

                    }**

                    rdr.Close();

                    //while (rdr.Read())
                    //{
                   //     string blah = rdr[2].ToString();
                   //     treeView1.Nodes[0].Nodes.Add(blah);
                  //  }
                  //  rdr.Close();

                    dbConn.Close();
                }
            }
            catch (OleDbException y)
            {
                Console.Error.WriteLine("Error: Failed to create a database connection. \n{0}", y.Message);
            }

Answer 1

Flip the loop:

while (rdr.Read())
{
    for (int y = 0; y <= numberColumns; y++)         
    {
        string childData = rdr[y].ToString();
        treeView1.Nodes[y].Nodes.Add(childData);
    }
}