英语翻译1.Answer the following questions.(4 points for each ques

英语翻译
1.Answer the following questions.(4 points for each question.)
1）List four Data Models.
2）List two disadvantages of database system.
3）List five main functions of database administrator.
4）What is the procedural language?What is the nonprocedural language?
5）What is Transaction?
2.Consider the teaching database below:
Students Students(StudentNo,StudentName,Age,Sex)
Courses Courses(CourseNo,CourseName ,Teacher)
Study Student2Course(StudentNo,CourseNo,Grade )
1) Give SQL DDL definition of this database.Identify referential-integrity constraints that should hold,and include then in the DDL definition.
2) Give an expression in SQL for each of ther following queries.:
（1）Find the average age of the students who choose CourseNo C4.
（2）find the average grade of each course teached by Wang Wei
（3）find the Students number and the course number of the students,
whose grade is NULL ,from SC.
（4）Find the name and age of all students whose surname is ZHANG.
(Chinese name order).
（5）Find the name and age of all the schoolboys whose age is higher than the average age of schoolgirls.
3.Using Armstrong’s axioms to Proof the union Rule:
if α → β and α → γ then α → βγ
4.Translate the following queries into relational algebra,tuple Relational Calculus and domain Relational Calculus.
1）select loan_number
from loan
where branch_name = ‘Perryridge’ and amount > 2000
2）select customer_name,borrower.loan_number,amount
from borrower,loan
where borrower.loan_number = loan.loan_number
and branch_name = Perryridge’
6.Write a SQL trigger to carry out the reorder for a warehouse.
Suppose the warehouse has the following tables:
inventory (item,level):How much of each item is in the warehouse.
minlevel (item,level ) :What is the minimum desired level of each item.
reorder (item,amount ):What quantity should we re-order at a time
orders (item,amount ) :Orders to be placed (read by external process)
7.R = (A,B,C,G,H,I)
F = {A→B A →C CG→H CG →I B→ H}
Calculate the closure of attributes (AG)+,
Is AG is a candidate key of .
小弟实在看不懂,急用,

1.回答下列问题.(四分问题.)
1)四数据模型.
二)列出两个缺点的数据库系统.
三)列出五大功能的数据库管理员.
四)程序语言是什么?什么是nonprocedural语言吗?
五)什么是交易吗?
在教学中2.Consider如下:
学生的学生(StudentNo、年龄、性别、StudentName).
课程的课程(CourseNo,CourseName,就是夫子.)
研究Student2Course(StudentNo,CourseNo、品位).
1)给SQL数据库定义的DDL).识别referential-integrity约束,应持,包括然后在DDL定义.
二)给一个表达式,在SQL对于每一种特产queries.之后.
(1)发现学生的平均年龄选CourseNo C4植物.
(二)发现平均品位的每门课程教由王炜
(三)发现学生的数量和课程的学生人数,
其为NULL,从供应链.
(四)找到了所有的学生姓名和年龄的姓张.
(中文名称外,所有部份订单).
(五)找到了所有的姓名和年龄的学生其年龄高于女生的平均年龄.
3.使用阿姆斯壮定理证明欧盟规则:
如果α→α和ββγ→→γ然后α)
4.将下列疑问到关系代数、微积分及相关领域元组关系演算.
1)选择贷款_号码
从贷款,
分支机构所在地的省、自治区、直辖市的Perryridge”的名称,数量= > 2000吗
(2)选择用户名称,borrower.loan _号码、金额
从借款人贷款
在borrower.loan _数量= loan.loan _号码吗
与分公司名称Perryridge = '
6.写一个SQL触发进行改组为一个仓库.
假设这个仓库有下列表格.
库存(项目):多少,均是在仓库里.
minlevel(项目、水平):什么是最小的期望每个物品的水平.
订货(项目)的数量,我们应该整合的一段时间
订单量(项目):命令,要通过外部的过程(读).
7.R =(A、B、C、G、H、我).
女= {一→B→C CG→H CG→我B→H)
就算关闭属性(AG)+,
公司是一个候选关键的R .
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