<!-- Collection of code snippets by Arne Vajhøj -->
<!-- posted to eksperten.dk, usenet and other places (2002-now) -->
<?php
    //$xf1 = 3;
    $xf2 = 'BB';
    $con = new mysqli('localhost', 'root', '', 'Test');
    if(mysqli_connect_errno()) die(mysqli_connect_error());
    $first = true;
    $sql = 'SELECT f1,f2 FROM t1';
    $typ ='';
    if(isset($xf1)) {
        $sql .= $first ? ' WHERE' : ' AND';
        $sql .= ' f1 = ?';
        $typ .= 'i';
        $val[] = &$xf1;
        $first = false;
    }
    if(isset($xf2)) {
        $sql .= $first ? ' WHERE' : ' AND';
        $sql .= ' f2 = ?';
        $typ .= 's';
        $val[] = &$xf2;
        $first = false;
    }
    if($stmt = $con->prepare($sql)) {
        call_user_func_array(array($stmt, 'bind_param'), array_merge(array($typ), $val));
        $stmt->execute();
        $stmt->store_result();
        $stmt->bind_result($f1, $f2);
        while ($stmt->fetch()) {
            print $f1 . ' ' . $f2 . "\n";
        }
        $stmt->close();
    } else {
        die($con->error);
    }
    $con->close();
?>