PHP - como puedo modificar el texto de una columna

<?php

  echo "Dia de Registro " . date("d-m-Y") . "<br>";

  date_default_timezone_set("America/New_York");

  echo "Hora de Registro " . date("h:i:sa"). "<br>";

  $link = mysql_connect("localhost", "root", "");

	 mysql_select_db("mibase", $link);

  $result = mysql_query("SELECT COL_6,COL_9,COL_28 FROM table_3", $link);

	echo "<table border = '1'> \n";

	echo "<tr><td>COL_6</td><td>COL_9</td><td>COL_28</td></tr> \n";

	while ($row = mysql_fetch_row($result)) {

	echo "<tr><td>$row[0]</td><td>$row[1]</td><td>$row[2]</td></tr> \n";

	  }

	echo "</table> \n";

?>

SELECT COL_6 FROM table_3...