how to remove duplicates php array_unique not working

Question

I try using array_unique(); but not working this is my code please help me what i doing wrong? I want display all tags without duplicates

ID | TAGS
1 | rock, punk, jazz
2 | pop, rock, classic
3 | jazz, blues, rock
4 | rock, rap, metal

$wynik = mysql_query("SELECT * FROM nabk_t_item_tags") or die('Błąd zapytania');
if (mysql_num_rows($wynik) > 0) {
    while ($r = mysql_fetch_assoc($wynik)) {
        $input = $r['tags'];
        $fields = explode(',', $input);
        $fields2 = array_unique($fields);
        foreach ($fields2 as $field) {
            echo '"' . $field . '",';
        }
    }
}

Answer 1

Try this code.

if (mysql_num_rows($wynik) > 0) {
    $used=array();
    while ($r = mysql_fetch_assoc($wynik)) {
        $input = $r['tags'];
        $fields = explode(',', $input);
        foreach($fields as $tg){
            if(!isset($used[$tg])){
                echo '"' . $tg . '",';
                $used[$tg]=" ";
            }   
        }
    }
    unset($used);
}