Database Modelling

A conceptual model includes :

• Entities, Attributes, Unique Identifiers and Relationships

• Only Entities, Attributes and Unique Identifiers
  

• Only Entities, Attributes and Relationships
  

• Only Entities and Relationships
  

The components of a relationship include all of the following except :

• Names

• Relational Integrity

• Cardinality

• Optionality

The Physical Model is derived from the Logical Model. True or False?

• True

• False

A foreign key is a column or combination of columns in one table that uniquely identifies a row of another table.  True or False?

• True

• False

The cardinality of a relationship can be _____________. (Choose two)

• one or more

• one to one

• many to many

• one and only one

A table must have a primary key. True or False?

• True

• False

In the relational model, relationships between relations or tables are created by using?

• Foreign key

• Composite keys

• Primary keys

• Candidate keys

When mapping a relationship for an ERD diagram both sides of the relationship have to be mapped.  True or False?

• True

• False

In an ERD diagram how is an optional relationship represented ?

• textual

• hierarhical

• technical

• graphical

Primary UIDs are:

• Mandatory in data modeling

• Useful as an alternative means of identifying instances of an entity, independent of their datatype

• Always comprised of numbers

• Optional in data modeling.