19、查找表中所有姓刘的职工的工号，部门，薪水
select emp_no,emp_name,dept,salary
from employee
where emp_name like '刘%'
20、查找所有定单金额高于2000的所有客户编号
select cust_id
from sales
where tot_amt>2000
21、统计表中员工的薪水在4000-6000之间的人数
select count(*)as 人数
from employee
where salary between 4000 and 6000
22、查询表中的同一部门的职工的平均工资，但只查询"住址"是"上海市"的员工
select avg(salary) avg_sal,dept
from employee
where addr like '上海市%'
group by dept
23、将表中住址为"上海市"的员工住址改为"北京市"
update employee
set addr like '北京市'
where addr like '上海市'
24、查找业务部或会计部的女员工的基本信息
select emp_no,emp_name,dept
from employee
where sex='F'and dept in ('业务','会计')
25、显示每种产品的销售金额总和，并依销售金额由大到小输出
select prod_id ,sum(qty*unit_price)
from sale_item
group by prod_id
order by sum(qty*unit_price) desc