Conceptual Design

Question 1

What does an oval denote in an E/R Diagram?

Answer 1

Attribute

Question 2

What does a rectangle denote in an E/R Diagram?

Answer 2

Entities

Question 3

What does a diamond denote in an E/R Diagram

Answer 3

Relationship

Question 4

What kind of attribute is underlined?

Answer 4

Key Attributes

Question 5

What kind of attribute is double-circled?

Answer 5

Multi-valued Attributes

Question 6

What kind of attribute is circled with a dotted line?

Answer 6

Derived Attributes

Question 7

What kind of attribute is circled with a thick line?

Answer 7

Composite Attributes

Question 8

Could a key value also be a special attribute?

Answer 8

No

Question 9

What is a weak entity type?

Answer 9

Entities existence dependant on an identifying relationship

Question 10

How can you identify weak entities?

Answer 10

Partial keys referring to foreign keys

Question 11

How is cardinality represented?

Answer 11

1 or M above the linking relationship line

Question 12

How is participation represented?

Answer 12

Single (partial) or double (total) linking relationship lines

Question 13

How is multiplicity represented?

Answer 13

Upper and lower bound (U,L) above a linking line

Question 14

What is a super key?

Answer 14

Attribute or set of attributes uniquely identifying a row

Question 15

What is a candidate key?

Answer 15

Superkey with no subsets also being a superkey

Question 16

What are the key attributes of a candidate key?

Answer 16

unqiueness and irreducibility

Question 17

What is a primary key?

Answer 17

Candidate key used to identify a row

Question 18

What is a foreign key?

Answer 18

Attribute within a relation matching candidate key of some relation

Question 19

What is entity integrity?

Answer 19

Primary keys cannot be null

Question 20

What is referrential integrity?

Answer 20

Foreign keys must match a candidate key of another row or must be null