04 ER Diagram

Question 1

what is entity

Answer 1

1. unique object
2. has a set of attributes
3. each attribute represented by a datatype

Question 2

what is entity set

Answer 2

a collection of entities

Question 3

what is a relationship

Answer 3

1. association among 2 or more entities

2. can be identified by entity keys

Question 4

what is a relationship set

Answer 4

a collection of similar relations

Question 5

relationship types

Answer 5

1 - 1
1 - many
many - 1
many - many

Question 6

types of constraits

Answer 6

1. participant constraint
   - at least 1
2. key constraint
   - at most 1