26、选取编号界于'C0001'和'C0004'的客户编号、客户名称、客户地址
select CUST_ID,cust_name,addr
from customer
where cust_id between 'C0001' AND 'C0004'
27、计算出一共销售了几种产品
select count(distinct prod_id) as '共销售产品数'
from sale_item
28、将业务部员工的薪水上调3%
update employee
set salary=salary*1.03
where dept='业务'
29、由employee表中查找出薪水最低的员工信息
select *
from employee
where salary=
(select min(salary )
from employee )
30、使用join查询客户姓名为"客户丙"所购货物的"客户名称","定单金额","定货日期","电话号码"
select a.cust_id,b.tot_amt,b.order_date,a.tel_no
from customer a join sales b
on a.cust_id=b.cust_id and cust_name like '客户丙'