pls suggest me what is the problem in my code

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C#3.5

dear frnds.
i have datatable and i am fill this datatable with the value of database table which have already a row in it but when i m load datatable using connected mode it give not me 1 row data to me, why


suggest me
my code is this



string sql = "select * from " + checkedListBox2.SelectedItem.ToString() + "";
Npgsql.NpgsqlCommand cmd = new Npgsql.NpgsqlCommand(sql, con);

using (Npgsql.NpgsqlDataReader rdr = cmd.ExecuteReader())
                            {
                                while (rdr.Read())
                                {
                                   
                                    dbdt.Load(rdr)
}
 for (int b = 0; b < dbdt.Rows.Count; )
                                    {
 string str = dbdt.Rows[b][chklistindex2].ToString();

                                        if (strg == str)
                                        {
                                            MessageBox.Show("find");
                                        }
                                        else if (strg!=str)
                                            {
                                                b++;
 
                                            }                                        
                                        else
                                        {
                                            using (var conn = new Npgsql.NpgsqlConnection(System.Configuration.ConfigurationManager.ConnectionStrings["test"].ToString()))
                                            using (var cmd1 = conn.CreateCommand())
                                            {
                                                conn.Open();
                                                cmd1.CommandText = "insert into " + checkedListBox2.SelectedItem.ToString() + " ( " + checkedListBox2.SelectedItem.ToString() + " ) values('" + strg + "')";
                                                var result = cmd1.ExecuteNonQuery();
                                            }
                                        }
                                    }
                         


this is my code and my database table (f_name)


it have 2 column id and f_name
and value in it is 1 and kavita respectively on first index

but my above code dose not load this data into datatable


why if i am add a new row in database then it load the data form second row in datatable


pls help me