使用内部连接和整理记录降序

Question

我正在使用两个表（student_class和class）在我的数据库中。我有一个查询下面显示class有students。但这不是我所期待的。如何显示有学生但显示结果的班级，以便最大席位下降。会计数需要吗？

SELECT 
    class.class_name 
FROM 
    class 
INNER JOIN 
    student_class ON class.class_id = student_class.class_id; 

表：

Student_class：

CLASS_ID STUDENT_ID 
---------- ---------- 
     2   12 
     2   11 
     2   2 
     7   5 
     7   6 
     7   7 
     7   8 
     7   9 
     9   2 
     9   11 
     9   12 
     10   20 
     10   2 
     10   4 

Class：

CLASS_ID CLASS_NAME   TEACHER_ID MAX_SEATS_AVAILABLE 
---------- ------------------- ---------- ------------------- 
     1 Intro to ALGEBRA   11     12 
     2 Basic CALCULUS    2     10 
     3 ABC and 123     1     15 
     4 Sharing 101     8     10 
     5 Good Talk, Bad Talk   9     20 
     6 Nap Time      1     21 
     7 WRITing 101     5     10 
     8 Finger Painting    9     14 
     9 Physics 230     2     20 
     10 Gym       5     25 

Answer 1

BY语句只需使用命令：

SELECT class.class_name FROM class INNER JOIN student_class ON class.class_id = student_class.class_id 
ORDER BY class.max_seats_available DESC 

Answer 2

你不需要点数。只要做一个ORDER BY MAX_SEATS_AVAILABLE DESC。

SELECT class.class_name, class.max_seats_available FROM class INNER JOIN 
student_class ON class.class_id = student_class.class_id ORDER BY 
class.MAX_SEATS_AVAILABLE DESC; 

这可能会有所帮助。

Answer 3

如果只是需要order byMAX_SEATS_AVAILABLE试试这个：

SELECT class.class_name, class.MAX_SEATS_AVAILABLE 
FROM class 
INNER JOIN student_class ON class.class_id = student_class.class_id 
ORDER BY class.MAX_SEATS_AVAILABLE DESC