PHP PDO insert example

$insert = array("firstname"=>"value",
    "lastname"=> "value2");

insertDB("user", $insert);
function insertDB($table, $data) {
    global $dbh;
    $fields = array(); $params = array(); $boundparam = array();
    foreach($data as $field => $value) {
        $fields[] ="`".$field."`";
        $params[] = $value;
        $boundparam[] = "?";
    }

    $sql = "INSERT INTO `".$table."`".
        " (".implode(",",$fields).") VALUES (".implode(",",$boundparam).")";

    $stmt = $dbh->prepare($sql);
    return $stmt->execute($params);
}