创建关系

Question

我创建了下列表格并插入了几个值。

create table books 
(
bookid integer primary key, 
booktitle varchar(20), 
year integer, 
publisherid integer foreign key references publisher(publisherid), 
price integer, 
number integer 
) 

create table publisher 
(
publisherid integer primary key, 
publishername varchar(20) 
) 

create table author 
(
authorid integer primary key, 
authorname varchar(20) 
) 

create table bookauthor 
(
bookid integer foreign key references books(bookid), 
authorid integer references author(authorid), 
earnings integer 
) 

create table bookreference 
(
bookid integer foreign key references books(bookid), 
referencebook varchar(20), 
times integer 
) 

create table reviewer 
(
reviewerid integer primary key, 
reviewername varchar(20) 
) 

create table bookreview 
(
bookid integer foreign key references books(bookid), 
reviewerid integer foreign key references reviewer(reviewerid), 
score integer 
) 

现在，我要解决在SQL Server 2000中以下查询查找出版于2003年，由两个“萨默尔Tulpule”和“与Hemant Mahta”审查的所有书籍。我没有得到任何关于查询的想法。我怎么写它？

感谢， 普加

Answer 1

SELECT b.bookid as bookid 
FROM (books b INNER JOIN bookreview br ON (br.bookid=b.bookid)) 
     INNER JOIN reviewer r ON (br.reviewerid = r.reviewerid) 
WHERE year=2003 AND r.reviewername IN ('Sammer Tulpule', 'Hemant Mahta') 
GROUP BY b.bookid 
HAVING COUNT(r.reviewerid) >= 2 

显然，这是假设你没有在书评表中重复的条目。

Answer 2

(SELECT b.* FROM books b, bookreview br, reviewer rv WHERE b.year = 2003 AND br.bookid = b.bookid and br.reviewerid = rv.reviewerid and rv.reviewername = 'Sammer Tulpule') 
INTERSECT 
(SELECT b.* FROM books b, bookreview br, reviewer rv WHERE b.year = 2003 AND br.bookid = b.bookid and br.reviewerid = rv.reviewerid and rv.reviewername = 'Hemant Mahta') 

我对飞打字所以有可能是小错误，但你得到的总体思路...