How to use OleDbConnection or SqlCommand to read Schema and database records

                // Creates a SqlDataReader instance to read data from the table.
                SqlDataReader dr = command.ExecuteReader();

                // Retrieves the schema of the table.
                DataTable dtSchema = dr.GetSchemaTable();

                // Writes the column headers.
                StreamWriter sw = new StreamWriter( fileOut, false, Encoding.Default );// Creates the CSV file as a stream, using the given encoding.
                string columnHeaderString = String.Join( ",", columnNames );//Convert an array to a comma-delimited string
                sw.WriteLine( columnHeaderString );

                // Reads the rows one by one from the SqlDataReader
                // transfers them to a string with the given separator character and writes it to the file.
                while ( dr.Read() )
                {
                    strRow = "";
                    for ( int i = 0; i < dr.FieldCount; i++ )
                    {
                        strRow += Convert.ToString( dr.GetValue( i ) );
                        if ( i < dr.FieldCount - 1 )
                        {
                            strRow += ",";
                        }
                    }
                    sw.WriteLine( strRow );
                }

                // Closes the text stream and the database connection.
                sw.Close();
                conn.Close();
            }
            catch ( Exception exception )
            {
                Console.WriteLine( exception );
                Thread.Sleep( 3000 );
                using ( TextWriter tw = new StreamWriter( fileLogFullPath ) )
                {
                    tw.WriteLine( DateTime.Now + "Error: " + exception.ToString() );
                }

                //Explicitly close - don't wait on garbage collection.
                connOleDB.Close();
                //Console.WriteLine( "Connection Closed." );
                // Closes the text stream and the database connection.
                conn.Close();
                return 0;
            }
            finally
            {
                //Explicitly close - don't wait on garbage collection.
                connOleDB.Close();
                //Console.WriteLine( "Connection Closed." );
                // Closes the text stream and the database connection.
                conn.Close();
            }
           
            return 1;
        }
    }
}

I have taken help from various sources for the code and I extend my most grateful thanks; I would include references but I've lost the links during my extensive searching.