Entity Relationship Modelling Flashcards
1
Q
Advantages of a database approach
A
- Control of data redundancy
- Data consistency
- Sharing of data
- Improved data integrity and data independence
2
Q
Disadvantages of database approach
A
- Complexity
- Cost of DBMS
- Cost of conversion
- Performance
- Higher impact of failure
3
Q
Entity
A
A set of objects that share the same properties
4
Q
Relationship
A
A set of meaningful associations between participating entities
5
Q
Attribute
A
A piece of data that describes an entity
6
Q
Primary key
A
A column that contains values that uniquely identify each row
7
Q
What are the multiplicity constraints?
A
Cardinality and Participation
8
Q
Cardinality
A
The maximum number of possible relationship occurrences in which a certain entity can participate in
9
Q
Participation
A
If all or only some entity occurrences participate in a relationship
10
Q
Recursive relationships
A
Where only one entity participates more than once but in different roles
11
Q
Domain
A
A set of values that can be stored in a column of a database table
