如何在mysql中按特定顺序排列？

Question

我有这张桌子

name        level
Dion        Leader
Roy         Member
Gerald      Member
Boyz        Assistant
Jade        Member
Gulliver    Leader
Ananda      Assistant
Vervada     Member

我想在此表中执行ORDER BY。所以，第一个显示的是Leader，然后是助手，然后是成员，并且它们也按照他们的名字排序。

我正在寻找的输出：

name        level
Dion        Leader
Gulliver    Leader
Ananda      Assistant
Boyz        Assistant
Gerald      Member
Jade        Member
Roy         Member
Vervada     Member

我当前的查询是（虽然没有提供正确的输出）：

SELECT name,level FROM t_user ORDER BY level='Leader' DESC, level='Assistant' DESC

注意：如果可能，查询必须尽可能轻/快。因为t_user有5k ++行。