Ch4

Question 1

compoennts of relational model

Answer 1

data strcutue

data manipulation

data integrity

Question 2

data strcurue

Answer 2

tables & keys

Question 3

data manipulation

Answer 3

what are the sql operations to retrieve or modofy data

Question 4

data integirty

Answer 4

mechanisms for implementing business rules that maintain integrity of data

Question 5

whaat is a relation

Answer 5

named 2D data!

rows (Records) columns(Attributes/fields)

Question 6

domain constraints

Answer 6

constrain allowable value for an attribute

Question 7

entity integ constraitns

Answer 7

all PK not Null and unique

Question 8

referential integrity constirans

Answer 8

rules that maintian consitency between the rows of 2 related tables

Question 9

what is referential integirty

Answer 9

if a FK is not null, then the insance it poitns to MUST exist

Question 10

3 approaches to ref integ

Answer 10

1, restrict: dont allow parent side if related drows exist inn dep side
2. cascade: auto delete dep that corespon with parent to be deleted
3. set to null: set fk to null if parent side deleted

Question 11

how ar eref integrity constraints dwan?

Answer 11

via arrows forom DEPENDANT TO PARENT TABLE

Question 12

Binary relations mapping
1:M
1:1
M:N

Answer 12

1:M: pk on one side becomes fk on nany side

1:1 pk on mandatory becomes fk on optional

m:n: create a new relation with pk of 2 ents as pk

Question 13

associate ents mapping
- id not assigned
- id assigned

Answer 13

not assigned: Def PK for the association relation is pk of 2 ents

assigned: natural and pfamiliar to end users

Question 14

Unary relationships
1:M
M:M

Answer 14

1:M- recursive fk in the same relation

M:M one for ent type on eofor associative relation in which the PK has 2 attributes

Question 15

mpaping ternanry

Answer 15

associate ent has a fk to each ent in relatioship

Question 16

mapping generlaizaiton/specializaiton

supertype/subtype to realitons

Answer 16

take the pk of the highest ent and then use the first letter and then create unique ids

Question 17

what is data nromalizaiton

Answer 17

tool to validate and improve logical design TO AVOID DUPLICATION! AN DBE WELL STRUCTURED

Question 18

What is a well structured relations

Answer 18

• min data redundancy, allow users to insert, delete and update rows w/o causing data inconsistenciesg

Question 19

goal of well structured relations: avid anomalies (3 types)

Answer 19

insertion: adding new rows forces user to crate duplicate data

deletion: deleting rows may cause a loss of data

modificaiton: changing data forces changes oto ther rows because of duplciation

Question 20

tabble w/mv attribute
–remvoe MV
first normal form
– remove partial depend
second normal form
– remove transitive dpeend
third nomal form
– remove remainng anomalies from multiple cand kess
boyce-codd
– remove mv depend
fourht normal form
– remove any left anomalies
fifth normal for

Answer 20

–
multivalues
partial depend
transitive depend
remaiing anomalies
multive depend
remaining anomalies

mptrmr

mp trudeau ran more runs

Question 21

what is a functional dependncy

Answer 21

value of one attirbute determines the value of another attirbute

Question 22

what is a candidate key

Answer 22

unieuq identifier (a candidate to be the PK!)

each non ey field is functionally dependant on every can key!

Question 23

no transitive depends

Answer 23

no functional depeds on no pk attirbutes! the pk is a determinant for another attribute whic in tur determinant for a 3rd

Question 24

The attribute on the left-hand side of the arrow in a functional dependency is the:

Answer 24

DETERMINANT!!!

DETERMINANT –> DEPENDANT

Question 25

A functional dependency in which one or more nonkey attributes are functionally dependent on part, but not all, of the primary key is called a ________ dependency.
Question

Answer 25

PARTIAL FUCNITONAL

Question 26

A functional dependency between two or more nonkey attributes is called a:

Answer 26

TRANSITIVE

Question 27

When a regular entity type contains a multivalued attribute, one must:

Answer 27

2 new relation, one contaiining mv

Question 28

customer ID in the customer table??

Answer 28

candidate

Question 29

first nf: all mv attirbutes are out

SECOND ND: NO mv, non key attirbutes solely dpeend on PK but contains transitive depends!

fourth nf: MV DEPENDANCIES ARE DEALT

boycodd: removes remaining func depends

Question 30

A relation that contains no multivalued attributes and has nonkey attributes solely dependent on the primary key but contains transitive dependencies is in which normal form?

SECONDD

Question 31

Which of the following is NOT a reason to create an instance of a relational schema with sample data?

SAMPLE DATA CAN REVESRSE DB ERRORS

Question 32

CONSTRAINT B/W 2 ATTIRBUTES IS CALELD A FUNCTIONAL DEPENDANCY

Question 33

ALT NAME FOR ATTRIRBUE

Answer 33

ALIAS

Question 34

COMPOSNENT QUESTION

Answer 34

COMP IS ALWAYS USED IN ONLY ONE ITEM

Question 35

A domain definition consists of all of the following components EXCEPT:

Answer 35

INTEGRITY CONSTRIANTS

Question 36

A functional dependency between two or more nonkey attributes is called a:

Answer 36

TRIANSSITIVE