Den här lösningen kan hjälpa dig
$sql = "SELECT a.COUPONID, a.TRUSTANDUSEID FROM `custom_redemptions` a WHERE a.couponid = 3";
$types = '';
$params = array(&$types);
if ($branchid != null) {
$sql .= " AND a.branchid = ?";
$types .= 's';
$params[] = $branchid;
}
if ($chainid != null) {
$sql .= " AND a.chainid = ?";
$types .= 's';
$params[] = $chainid;
}
if ($stmt = $this->dbCon->prepare($sql)) {
call_user_func_array(array($stmt, 'bind_param'), $params);
$stmt->execute();
$stmt->bind_result($couponid, $trustanduseid);
while ($stmt->fetch()) { echo $couponid; }
$stmt->close();
}