如何仅选择不在特定组中的学生(例如group.id = 1)？

我做了一些搜索并尝试使用子查询,但只获得一个空集……

select * From students where not exists (select students.* from students left join students_groups on students_groups.student_id = student.id where students_groups.group_id = 1);

我该怎么查询？提前多了！

编辑
好吧,似乎以下两个终于有效……任何人都可以解释为什么我不需要加入表来工作？

select * from students where not exists (select * from students_groups where students_groups.student_id = student.id and student_groups.group_id = 1);

select * from students where id not in (select student_id from students_groups where group_id = 1);