Ayuda con "TABLAS"

[tampon]

Código php:

echo "<table>
<tr>
<th>columna 1</th>
<th>columna 2</th>
<th>columna 3</th>
</tr>";
 
while($row = mysql_fetch_array($sql))
  {
  echo " <tr>";
  echo "<td>" . $row['columna_bd1'] . "</td>";
  echo "<td>" . $row['columna_bd2'] . "</td>";
  echo "<td>" . $row['columna_bd3'] . "</td>";
  echo "</tr>";
  }
echo "</table>";