联结表

1. select vend_name, prod_name, prod_price from vendors, products order by vend_name, prod_name; 返回所有的组合，笛卡尔积。
2. select vend_name, prod_name, prod_price from vendors inner join products on vendors.vend_id = products.vend_id 内联结(等值连接)
3. select prod_name, vend_name, prod_price, quantity from orderitems, products, vendors where products.vend_id = vendors.vend_id and orderitems.prod_id = products.prod_id and order_num = 20005 多表连接
4. select Contact(RTrim(vend_name), '(', RTrim(vend_country), ')') as vend_title from vendors order by vend_name Contact生成字符串连接
5. select cust_name, cust_contact from customers as c ,orders as o, orderitems as oi where c.cust_id = o.cust_id and oi.order_num = o.order_num and prod_id = 'TNT2'
6. select customers.cust_id, order.order_num from customers left outer join orders on customers.cust_id = orders.cust_id;
7. select customers.cust_id, order.order_num from customers right outer join orders on customers.cust_id = orders.cust_id;
8. select. customers.cust_name, customers.cust_id, COUNT(order.order_name) as num_ord from customers inner join orders on customers.cust_id = orders.cust_id group by customers.cust_id;