AQA A level Databases 2: Normalisation

A relationship is?

• A list of keys or keywords which identify a unique record and can be used to search and sort records more quickly

• A field in a table that refers to the primary key in another table

• The extent to which a database has been normalised

• The way in which two entities in two different tables are connected

A field of one table which is also a primary key of another table. It is used to establish links between entities in the database.

• Primary key

• Foreign key

• Attribute

• Relationships

Normally, foreign key is found in child table which serves the purpose of connecting to the parent table. 

• False
• True

For the top table (i.e. Order Table), which is the primary key?

• Order Date

• Customer ID

• Order Number

• Order Table

For the top table (i.e. Order Table), which is the foreign key which connects to the bottom (Customer) table?

• Customer Key

• Customer ID

• Order Number

• Order Date

What is the entity attribute that uniquely identifies an instance in a table called?

• Secondary key

• Foreign key

• Compound key

• Primary key

Zero or one instance of entity A can be associated with zero or one instance of entity B, and zero or one instance of entity B can be associated with zero or one instance of entity A.

What type of relationship is described?

• One-to-one

• One-to-many

• Many-to-one

• Many-to-many

An ER diagram shows relationships between:

• Tables in a relational database. 
• Rows in a relational database. 
• Records with foreign keys. 
• Two items about which there is data kept. 

Entities (tables) have attributes (fields). 

• True
• False

Many users access many servers. Why is this statement not a good inclusion in an ER diagram?

• It creates duplicates and therefore redundancy

• It is not a good idea to access too many servers

• It is syntactically incorrect

• It involves a bridging entity