CS计算机代考程序代写 Exercise 1 – Solution

Exercise 1 – Solution
Q1

Q2

Q3

(a) Entity types: BANK, ACCOUNT, CUSTOMER, LOAN

(b) BANK_BRANCH, BranchNo, BRANCHES.

(c) The partial key BranchNo in BANK-BRANCH specifies that the same BranchNo value may occur
under different BANKs. The identifying relationship BRANCHES specifies that BranchNo values are

uniquely assigned for those BANK-BRANCH entities that are related to the same BANK entity. Hence,

the combination of BANK Code and BranchNo together constitute a full identifier for a BANK-BRANCH.

Q4

The requirements may be stated as follows: Each BANK has a unique Code, as well as a Name and

Address. Each BANK is related to one or more BANK-BRANCHes, and the BranhNo is unique among

each set of BANK-BRANCHes that are related to the same BANK. Each BANK-BRANCH has an

Address. Each BANK-BRANCH has zero or more LOANS and zero or more ACCTS. Each ACCOUNT

has an AcctNo (unique), Balance, and Type and is related to exactly one BANK-BRANCH and to at least

one CUSTOMER. Each LOAN has a LoanNo (unique), Amount, and Type and is related to exactly one

BANK-BRANCH and to at least one CUSTOMER. Each CUSTOMER has an SSN (unique), Name,

Phone, and Address, and is related to zero or more ACCOUNTs and to zero or more LOANs.

Q5

Entity 1 Cardinality Ratio Entity 2

1. Student

1-many

A student may have more

than one social security

card (legally with the

same unique social

security number), and

every social security

number belongs to a

unique student.

SocialSecurityCard

2. Student

Many-many

Generally students are

taught by many teachers

and a teacher teaches

many students.

Teacher

3. ClassRoom

Many-many

Don’t forget that the wall

is usually shared by

adjacent rooms.

Wall

4. Country

1-1

Assuming a normal

country under normal

circumstances having one

CurrentPresident

president at a time.

5. Course

Many-many

A course may have many

textbooks and a text book

may be prescribed for

different courses.

TextBook

6.
Item (that can be

found in an order)

Many-many

Assuming the same item

can appear in different

orders.

Order

7. Student

Many-many

One student may take

several classes. Every

class usually has several

students.

Class

8. Class

Many-to-1

Assuming that every class

has a unique instructor. In

case instructors were

allowed to team teach,

this will be many-many.

Instructor

9. Instructor

1-1

Assuming every instructor

has only one office and it

is not shared. In case of

offices shared by 2

instructors, the

relationship will be 2-1.

Conversely, if an

instructor has a joint

appointment (in two

departments) and offices

in both departments, then

the relationship will be 1-

2. In a very general case,

it may be many-many.

Office

10.
E-bay Auction

item

1-many

1 item has many bids and

a bid is unique to an item

(assuming a regular

auction format).

E-bay bid