如果要显示出版社名称,图书表至少要有出版社id;
create view as
select A.bookname,B.pubname,
nvl(C.downloadnum) as downloadnum, nvl(C.looknum) as looknum
from 图书表 A,出版社表 B,图书的浏览表 C
where
A.出版社id = B.id
and A.id = C.bookid(+)
create view as
select A.bookname,B.pubname,
nvl(C.downloadnum) as downloadnum, nvl(C.looknum) as looknum
from 图书表 A,出版社表 B,图书的浏览表 C
where
A.出版社id = B.id
and A.id = C.bookid(+)
select a.id,a.bookname,b.pubname,nvl(c.downloadnum,0),nvl(c.looknum,0)
from 图书表 a,出版社表 b,图书的浏览表 c
where a.id=b.id
and a.id=c.id(+)
create view as
select A.bookname,B.pubname,
nvl(C.downloadnum) as downloadnum, nvl(C.looknum) as looknum
from 图书表 A,出版社表 B,图书的浏览表 C
where
A.出版社id = B.id
and A.id = C.bookid(+) 一样的啊