problem in search with levenshtein

i am trying a search with levenshtein but m stuck with a serious problem.The field "topic" in the database is a string of more than one word which m not able to solve with the type of search i am doing here.had there been one word in the string it would be fine but for such case its a total failure.

i also need to use the soundex() or some similar function as the entries in my database are no similar.and again one more problem php 4.4.2 that m using is case sensitive so levenshtein is not working fine.

m totally stuck.please fix the code.here is the code

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<?php
// input misspelled word

$trimmed=@$_GET['q'];
$input=trim($trimmed);


$arrWords=explode(" ",$input);

if(sizeof($arrWords)==0||$input==""){
echo"enter keyword";


echo"<a href=\"lev.php\">click here</a>";



}



$m=sizeof($arrWords);
echo"nkdkf$m";




$shortest = -1;



mysql_connect("localhost","root");

@mysql_select_db(test);

//foreach ($arrWords as $trimm){
//$query1 = "SELECT topic FROM forum_question WHERE topic LIKE \"%$trimm%\" ORDER BY id DESC" ;









$query1="select topic from forum_question";
$result1=mysql_query($query1);

$i=0;
$count=0;
while($r=mysql_fetch_array($result1)){
$topic[$i]=$r["topic"];
//echo $topic,"\n";
//echo"<br>";

//$toopic=explode(" ",$topic);
//$n=sizeof($toopic);
//for($k=0;$k<$n;$k++){
//$toopic[$i][$k]=$toopic[$k];
//echo $toopic[$i][$k];
//}
$i++;
$count++;
}








//foreach ($topic as $word) {


$i=0;
for($i=0;$i<$m;$i++){
for($j=0;$j<9;$j++){
//for($k=0;$k<$n;$k++){

$lev = levenshtein($arrWords[$i], $topic[$j]);

echo"$lev\n\n";


if ($lev == 0) {

// closest word is this one (exact match)
$closest = $topic[$j];
$shortest = 0;

// break out of the loop; we've found an exact match
break;
}


if ($lev <= $shortest || $shortest < 0) {
// set the closest match, and shortest distance
$closest = $topic[$j];
$shortest = $lev;


}

}

echo "Input word: $arrWords[$i]\n";
if ($shortest == 0) {
echo "Exact match found: $closest\n";
} else {
echo "Did you mean: $closest?\n";

}
$closest="";
$shortest=-1;
}
?>