查询有关数据库管理系统

Question

我想写这些查询

• 显示谁从来没有借出的诗集学生的名字。
• 显示借出5本以上书籍的学生的姓名。
• 显示学生姓名，书名，发行日期以及所有预订书籍的作者姓名。

查询我写了那么远是不工作的第一项任务

SELECT 
    name  
FROM 
    students 
INNER JOIN issued ON students.rollno = issued.rollno 
GROUP BY 
    issued.rollno 
HAVING 
    COUNT(issued.rollno)> 2 

Answer 1

给这些查询试试

select s.name from students s 
left join issued i on (s.rollno = i.rollno) 
left join bookcopy bc on (i.copyid = bc.copyid) 
left join books b on (bc.bookid = b.bookid) 
left join category c on (b.catid = c.catid and c.catname = 'Poetry') 
where c.catid is null 

select s.name, count(*) as from students s 
left join issued i on (s.rollno = i.rollno) 
group by s.name 
having count(*) > 5 

select s.name, b.title, a.authorname, i.issuedate from students s 
left join issued i on (s.rollno = i.rollno) 
left join bookcopy bc on (i.copyid = bc.copyid) 
left join books b on (bc.bookid = b.bookid) 
left join author a on (b.authorid = a.authorid);