3 Question about sql.

[wwchar]

pet(name, owner, species, sex, checkups, birth, death)

the number of pets of each species that each owner has.
the number of birds each owner has.
the total number of checkups each owner has made with all their pets.

[wwchar]

The number of distinct species of pet each owner has.
the number of birds each owner has.
the total number of checkups each owner has made with all their pets.

[feel8]

实在看不懂，在装金山词霸。。

[wwchar]

更新一下：有几个问题已经解决。
每个owner拥有的鸟的数目，我想让没有鸟的owner显示0，不知道有没有办法。

[ustb]

看了半天没有看到问什么？
不过像这样经典的数据库问题相信随便找本书也能搞定了。

[wwchar]

就是想让没有鸟的owner显示0，
用纯sql行不行

[wwchar]

pet(name,owner，species）
name:宠物名字
owner：所有者
species：宠物种类（鸟，狗....）
每个owner所拥有的鸟的数量。
关键是有些owner没有鸟，查询出来表中就没有该owner名字，
现在想要的结果最好能把没有鸟的owner，拥有鸟的数量是0，而不是不在表中出现。