Mmpn exercises
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mMpn Exercises. PAYMENT SeqNum. LOAN LoanID. CUSTOMER CustID. (0,n). (1,1). (1,1). (1,n). A car loan to a customer is paid back by regular monthly, numbered payments. Payments are identified by which loan and which payment number. PERSON SSN. PLAYER position. COACH. is_a. is_a.

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mMpn Exercises

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Mmpn exercises

mMpn Exercises

Database Principles


Mmpn exercises

PAYMENT

SeqNum

LOAN

LoanID

CUSTOMER

CustID

(0,n)

(1,1)

(1,1)

(1,n)

  • A car loan to a customer is paid back by regular monthly, numbered payments. Payments are identified by which loan and which payment number.

Database Principles


Mmpn exercises

PERSON

SSN

PLAYER

position

COACH

is_a

is_a

trains

(1,1)

(1,n)

  • Baseball teams consist of players and coaches. The former are known to play different positions. All players have a coach responsible for their training.

Database Principles


Mmpn exercises

ACCOUNT

BRANCH

AcctNum

Name

CUSTOMER

SSN

held with

(0,n)

(1,1)

(c,d)

(a,b)

(1,n)

  • Must a customer have accounts with only 1 branch?

  • Do branches share responsibility for accounts?

(e,f)

opens

(g,h)

(1,n)

No. h == n and c == 1

No. d == 1

Database Principles


Mmpn exercises

(e,f)

(0,n)

qualified to repair

PLANETYPE

TypeName

(1,n)

(g,h)

(a,b)

(1,1)

is of type

MECHANIC

SSN

(c,d)

repaired by

PLANE

PlaneID

(0,n)

(1,n)

(k,l)

date

(0,n)

(I,j)

  • What is the obvious mistake in the above diagram?

  • Does the model support the enterprise rule that there should always be a mechanic able to repair any plane in need?

(c,d)=(0,n). It should be (1,1)

No, e=0, a=1 implies there may be a planeand no mechanic qualified to repair it.

Database Principles


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