数据库 SQL应用题

10.题答案

select 课程号,总分,平均分,最高分,最低分(

select 课程号,

总分=sum(成绩),

平均分=sum(成绩)/count(*),

最高分=max(成绩),

最低分=min(成绩)

from 成绩

group by 课程号) as kc order by 平均分 desc

11.题答案

select 课程号,

平均分=sum(成绩)/count(*)

from 成绩

where 课程号='1001' or 课程号='1002'

group by 课程号

12.题答案

select 姓名,xs.学号,kc.平均分

from 学生 as xs

left join (select 学号,

平均分=sum(成绩)/count(*)

from 成绩

group by 学号) as kc on kc.学号=xs.学号

where kc.平均分>80

1.create database Readbook

on

(name=Readbook_data,filename='D:\server\Readbook_data.mdf',size=2mb,maxsize=10mb,filegrowth=1mb)

log on

(

name=Readbook_log,

filename='D:\server\Readbook_log.ldf',size=1mb,maxsize=5mb,filegrowth=1mb

)

go

2.use mybase

go

alter database mybase

add log file

(

name=Readbook2_log,

filename='D:\server\mybase2_log.ldf',size=2mb,maxsize=10mb,filegrowth=1mb

)

go

3.alter database mybase

remove file Readbook2_log

1 C 10 C 判断 1 对 2 错 3 错 4 对 5错

2 A 11 D 6 错 7 对 8 对

3 A

4 A

5 A

6 C

7 C

8 A

9 A

---