Try the following modified code of yours, if still not working then give the live URl where ur html output is displyed.
if (($getcolumns)||(mysql_errno == 0))
{
// Displying the headers
$i = 0;
echo "<table width='50%' id='sample_2'><thead><tr>";
while ($i < mysql_num_fields($getcolumns))
{
echo "<th align='center'>". mysql_field_name($getcolumns, $i) . "</th>";
$i++;
}
echo "</tr></thead>";
// Data Section
echo "<tbody>";
if (mysql_num_rows($getcolumns)>0)
{
while ($rows = mysql_fetch_array($getcolumns, MYSQL_ASSOC))
{
echo "<tr>";
foreach ($rows as $data)
{
echo "<td align='center'>". $data . "</td>";
}
echo "</tr>";
}
}else{
echo "<tr><td colspan='" . ($i+1) . "'>No Results found!</td></tr>";
}
echo "</tbody></table>";
}else{
echo "Error in running query :". mysql_error();
}