实验二 简单查询及子查询
一. 目的：
练习SQL.
二. 内容：
1. 练习查询语句:（Example3.4.1-3.4.3; Example3.4.6-3.4.14； Example3.5.1.-3.5.2). 操作内容截图如下：
CUSTOMERS :
AGENTS:
PROODUCTS:
ORDER;
2练习查询语句
Example3.4.4
select distinct cid from orders
where aid in (select aid from agents where city='Duluth' or city='Dallas');
Example3.4.2 Retrieve all information concerning agents based in Duluth or Dallas. select * from agents
where city in('Duluth','Dallas');
Example3.4.3
select cname,discnt from customers
where cid in(select cid from orders where aid in(select aid from agents where city in('Duluth','Dallas')));
Example3.4.6
select ordno from orders x where exists (select cid,aid from customers c,agents a
where c.cid=x.cid and a.aid=x.aid and c.city='Duluth' and a.city='New York);
Example3.4.7
select aid from agents where commission<=all (select commission from agents);
Example3.4.8
select cid,cname from customers
where discnt =some(select discnt from customers where city='Dallas' or city='
Boston');
Example3.4.9
select cid from customers
where discnt Example3.4.10 select distinct c.cname from customers c,orders x where c.cid =x.cid and x.aid='a05'; Example3.5.1 select city from customers union select city from agents;