Question

我有以下表格

subject(id,name,sem,branch) //Detail of subject in sem and branch
teacher(id,name,dept) //detail of teacher
student_teacher_mapping(sid,tid) //primary key of student and teacher
section(id,sec) //detail of sections
subject_section_mapping(sid,secid) //primary key of subject and section

我想获取分支“计算机科学”的主题名称和教师名称，sem = 3和section ='d'。

Answer 1

@Manish你看到你的表SUBJECT链接到SECTION，这将给我们一个SECTION，并且表SECTION没有链接到任何其他表，所以这里似乎有一个死胡同，数据库设计似乎是错误的。

Answer 2

最后，我在没有你帮助的情况下完成了这项工作：/

我换了一张桌子我的桌子是

subject(id,name,sem,branch) //Detail of subject in sem and branch
teacher(id,name,dept) //detail of teacher
section(id,sec) //detail of sections
sub_teacher_sec (subject_id,teacher_id,section_id) //primary key of subject,teacher and section

这是我的查询，以获取主题名称，教师名称和空间分支学期和部分值的部分

select sub.name,t.name,se.sec from subjects as sub
  join
sub_teacher_sec as sts
  on
sts.subject_id=sub.id
 join
teachers as t
  on
sts.teacher_id=t.id
 join
section as se
   on
sts.section_id=se.id
and  sub.semester=3 and sub.branch='CSE';

表中或查询中是否有任何更正请建议。

查询从表中获取数据

2 个答案: