Question

student table   teacher table    sports table     parents table
---------     --------------     ------------      ---------------
id  name        id  name        id  name           id    stud_id  fathername   mothername
------------   ------------    ------------        -----------------------------------------
1    S1           1     T1         1    SP1         1       1       xxxxxx       yyyyyyy
2    S2           2     T2         2    SP2         2      2        abc          aaa    
3    S3           3     T3         3    SP3 

student_teacher table               student_sports table
id    stud_id     teacher_id       id      sutd_id    sports_id
------------------------------     ------------------------------
1      1            1               1        1          1
2      1            2               2        1          2
3      1            3               3        1          3
4      2            2               4        3          2
5      2            3               5        3          3

如何编写查询以从所有表中获取学生S1的信息。例如，学生S1参加体育名称，教学生S1的教师姓名，学生S1父母信息。这里学生，老师，父表中的id是主键。 stud_id，teacher_id，sports_id是指学生，教师，体育表主键的外键。请帮我从表中获取学生S1的记录。提前致谢。

Answer 1

以下是解决方案：

select st.name as Student, t.name as teacher, sp.name as sports, p.fathername,p.mothername from student st,teacher t,sports sp,parents p,student_teacher s_t,student_sports s_s where s_t.stud_id=st.id and s_t.teacher_id=t.id and p.stud_id=st.id and s_s.stud_id=st.id;

Answer 2

您可以简单地使用where子句：

select S.name, T.name, SS.name, P.fathername, P.mothername 
from student S, teacher T, sports SS, parents P,student_teacher ST, student_sports SSP 
where S.id = ST.stud_id and T.id = ST.teacher_id and
S.id = SSP.stud_id and SS.id = SSP.sports_id and
S.id = P.stud_id

Answer 3

您需要合并student_teacher和student_sports表。没有办法嫁给哪位老师教某个学生参加某项运动。我们所知道的是学生1参加了第1,2和3项运动，并由老师1,2和3教授。我们不知道哪位老师参加了哪项运动。你应该这样：

student_sports_teacher table
+----+---------+-----------+------------+
| id | stud_id | sports_id | teacher_id |
+----+---------+-----------+------------+
|  1 |       1 |         1 |          1 |
|  2 |       1 |         2 |          2 |
|  3 |       1 |         3 |          3 |
|  4 |       2 |         1 |          2 |
|  5 |       2 |         2 |          3 |
+----+---------+-----------+------------+

完成后，您可以使用联接来获取所有数据：

SELECT * FROM student s
LEFT JOIN parents p ON s.id = p.stud_id
LEFT JOIN student_sports_teacher sst ON sst.stud_id = s.id
LEFT JOIN sports sp ON sp.id = sst.sports_id
LEFT JOIN teacher t ON t.id = sst.teacher_id

Answer 4

您可以使用内部联接

     select st.name as Student, t.name as teacher, sp.name as sports, 
          p.fathername,p.mothername 
     from student st
     Inner join student_teacher as st on st s_t.stud_id=st.id 
     Inner join teacher t on s_t.teacher_id=t.id 
     Inner join parents p on p.stud_id=st.id 
     Inner join student_sports ss on  ss.stud_id=st.id;

如何从表中检索学生信息？

4 个答案: