过滤与条件

Question

加入我有3个表，命名为

students (id, name) 
subjects (id, name, is_published) 
student_subjects (id, student_id, subject_id) 

进去student_subjects采取一个学生的科目。但也有地方student_subjects包含NULL subject_id一个学生

以下情况下对Students表

1;"John" 
2;"Ahmeah" 
3;"Dina" 
4;"Leo" 
5;"Lenon" 

主题表

1;"Computer Sci";1 
2;"Physics";1 
3;"Bio";1 
4;"Maths";0 

Student_subjects

1;1;1 
2;1;2 
3;1;4 
4;2;1 
5;2;3 
6;2;4 
7;3;2 
8;4;1 
9;5;NULL 

目前获取的所有数据学生与他们的主题学分也显示谁没有连接到他受到了学生的名字，我使用的查询，如下所示

SELECT 
    students.*, 
    inners.name 
FROM 
    students 
    LEFT JOIN (SELECT 
       student_id, 
       subjects.name 
       FROM 
       student_subjects 
       JOIN subjects ON (student_subjects.subject_id = subjects.id AND subjects.is_published = 1) 
      ) AS inners ON (inners.student_id = students.id) 

有没有更好的方式做同样的http://sqlfiddle.com/#!12/9cf93/12

Answer 1

SELECT s.*, su.name AS SubjName 
FROM students AS s 
LEFT JOIN student_subjects AS ss ON ss.student_id = s.id 
LEFT JOIN subjects AS su ON su.id = ss.subject_id 

请问与您列出的相同。那是你的追求？