query in php

I am doing a site that you should be able to search by sex, place and age. I can get it to search by all 3, but not if someone just does sex and place. Can anyone see what I'm doing wrong.

if ($search AND $sex_s AND $place_s AND $age_from AND $age_to)
{
$numresults = mysql_query("select * from user where sex like '$sex_s%' AND place like '$place_s%' AND (age between $age_from AND $age_to)");
$numrows=mysql_num_rows($numresults);
$string = "select * from user where sex like '$sex_s%' AND place like '$place_s%' AND (age between $age_from AND $age_to) limit $offset,$limit";
$result=mysql_query($string);
$URLNEXT = "&sex_s=$sex_s&age_from=$age_from&age_to=$age_to&place_s=$place_s&search=1&place=$place&sex=$sex";
}
elseif ($search2 AND $sex_s AND $place_s)
{
$numresults = mysql_query("select * from user where place like '$place_s%' AND sex like '$sex_s%'");
$numrows=mysql_num_rows($numresults);
$string = "select * from user where place like '$place_s%' AND sex like '$sex_s%' limit $offset,$limit";
$result=mysql_query($string);
$URLNEXT = "&sex=$sex_s&place=$place_s&searh2=1&place=$place&sex=$sex";

Sorry, it's getting too late in the day and all those $s are scary.
If it's coming from a form (which is most likely) then try:

$sql = "select * from user where ";

if (isset($sex)) {
$sql .= "sex = $sex and ";
}
if (isset($place)) {
$sql .= "place = $place and ";
}
if (isset($age)) {
$sql .= "age = $age";
}
$numresults = mysql_query($sql);

Please post this problem on PHP forum .you will get quick response from there.