Normalization CS

Normalisation is:

• Removing all necessary data from a database

• Organising a database to remove repeated entries and increase the accuracy of the data

• Putting fields from different tables into one big database

A relation is in 1NF if it doesn't contain any ____________?

• Determinants

• Repeating groups

• Null values in primary key fields

• Functional dependencies

A table is in 2NF if the table is in 1NF and what other condition is met?

• There are no functional dependencies.

• There are no null values in primary key fields.

• There are no repeating groups.

• There are no attributes that are not functionally dependent on the relation's primary key.

When you normalize a relation by breaking it into two smaller relations, what must you do to maintain data integrity?

• Remove any functional dependencies from both relations

• Assign both relations the same primary key field(s)

• Create a primary key(s) for the new relation

What is a functional dependency?

• when an non-key attribute is determined by a whole part of a COMPOSITE primary key.

• When a key field is changed and it conflicts with another key

• When a database function is dependant of the operation of another function to work correctly

• When data is a database is repeated for different entities

What is a foreign key?

• A unique identifier in a database

• A primary key of one table that appears in another table

• A field that should not be in a table and needs removing

Which of the following statements fully describes data in 2NF:

• When any repeating fields have been removed and the table is given a primary key

• When all repeating entries of data are removed and the fields in each table are directly related to the primary key and no fields are present that are not related to each other

• When all the fields in each table are directly related to the primary key

What is a composite primary key?

• A primary key that can be duplicated in the same table

• An attribute that is a primary key in another table

• A foreign key that is a primary key in more than one other table

• A primary key made up from two or more attributes

A table where all attributes are dependent on the primary key and are independent of each other, and no row contains two or more multi valued facts about an entity, is said to be in ____.

• 1NF

• 2NF

• 3NF

• 4NF

Problems in Relational Data Model are :

• Anomalies

• Information Redundancy

• None of the above