这在php / mysql中足够安全吗？

Question

我正在运行此查询以获取帖子，如果该成员有权访问它。是否足够安全，只需检查if($row)？

$sql = "SELECT f_title
            FROM fields
            INNER JOIN members
                ON m_group_id = f_group_id
                AND m_u_id = " . mysqli_real_escape_string($db_link, $_SESSION['u_id']) . "
                AND m_status > 0
            WHERE f_id = " . mysqli_real_escape_string($db_link, $_POST['id']) . "
            LIMIT 1";
$result = mysqli_query($db_link, $sql) or die(mysqli_error($db_link));
$row = mysqli_fetch_assoc($result);
if($row)
{
    echo 'Permission granted!';
}
else
{
    echo 'Permission NOT granted!';
}