数据库

    1：抽出部门，平均工资，要求按部门的字符串顺序排序，不能含
       有"human resource"部门，employee结构如下：employee_id,
       employee_name, depart_id,depart_name,wage
    答:
        select depart_name, avg(wage)
            from employee
                where depart_name <> 'human resource'
                group by depart_name
                order by depart_name
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    2：给定如下SQL数据库：Test(num INT(4)) 请用一条SQL语句返回
       num的最小值，但不许使用统计功能，如MIN，MAX等
   
    答:
        select top 1 num
        from Test
        order by num desc

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33.一个数据库中有两个表:
一张表为Customer，含字段ID,Name;
一张表为Order，含字段ID,CustomerID（连向Customer中ID的外键）,Revenue；
写出求每个Customer的Revenue总和的SQL语句。

建表
create table customer
(
ID int primary key,Name char(10)
)

go

create table [order]
(
ID int primary key,CustomerID int foreign key references customer(id) , Revenue float
)

go

--查询
select Customer.ID, sum( isnull([Order].Revenue,0) )
from customer full join [order]
on( [order].customerid=customer.id )
group by customer.id