我该如何获取我关注的人，但他们不关注？

Question

所以我有一个名为follow_sys的表，其中有三列id和follower和following包含关注者和跟随者的用户名，所以我想获取所有我追随者，但他们没有跟着我，我该怎么做？

我尝试了自我加入，但没有成功，我很困惑

    $sqlFollowing      = "SELECT * from follows_syds t1
                               join follows_syds t2 on
                               t1.follower != t2.following
                               where
                               t1.follower = ?
                               group by t1.id";
$Following         = $conn -> prepare($sqlFollowing);
$Following        -> bind_param('s',$getUser);
$Following        -> execute();
$FollowingGET      = $Following -> get_result();
$FollowingRows     = $FollowingGET -> num_rows;

while($b = $FollowingGET -> fetch_assoc()){

print_r($b);
echo "</br>";
}