A First Course in Database Systems - Solutions, summaries, and outlines. 2022 updated

Exercise 2.2.1a



For relation Accounts, the attributes are:



acctNo, type, balance



For relation Customers, the attributes are:



firstName, lastName, idNo, account



Exercise 2.2.1b



For relation Accounts, the tuples are:



(12345, savings, 12000),

(23456, checking, 1000),

(34567, savings, 25)



For relation Customers, the tuples are:



(Robbie, Banks, 901-222, 12345),

(Lena, Hand, 805-333, 12345),

(Lena, Hand, 805-333, 23456)



Exercise 2.2.1c

,For relation Accounts and the first tuple, the components are:



123456  acctNo

savings  type

12000  balance



For relation Customers and the first tuple, the components are:



Robbie  firstName

Banks  lastName

901-222  idNo

12345  account



Exercise 2.2.1d



For relation Accounts, a relation schema is:



Accounts(acctNo, type, balance)




For relation Customers, a relation schema is:



Customers(firstName, lastName, idNo, account)



Exercise 2.2.1e

,An example database schema is:



Accounts (

acctNo,

type,

balance

)

Customers (

firstName,

lastName,

idNo,

account

)



Exercise 2.2.1f



A suitable domain for each attribute:



acctNo  Integer

type  String

balance  Integer

firstName  String

lastName  String

idNo  String (because there is a hyphen we cannot use Integer)

account  Integer

, Exercise 2.2.1g



Another equivalent way to present the Account relation:



acctNo balance type

34567 25 savings

23456 1000 checking

12345 12000 savings




Another equivalent way to present the Customers relation:



idNo firstName lastName account

805-333 Lena Hand 23456

805-333 Lena Hand 12345

901-222 Robbie Banks 12345



Exercise 2.2.2



Examples of attributes that are created for primarily serving as keys in a relation: