Databases

Question 1

What is a relational database?

Answer 1

A database which recognises the difference between entities and uses different tables for entity.

Question 2

What is an entity?

Answer 2

An item of interest about which information is stored.

Question 3

What is a flat file?

Answer 3

A database that consists of a single file, usually about one entity.

Question 4

What is a primary key?

Answer 4

A unique identifier for each record in a table.

Question 5

What is a foreign key?

Answer 5

The attribute which links two tables together.

Question 6

What is a secondary key?

Answer 6

An index other than the primary key used to search and sort through the database with more convenience and speed.

Question 7

What is normalisation?

Answer 7

Process if coming up with the best layout for a relational database.

Question 8

What does normalisation try to accomplish?

Answer 8

• No redundancy
• Consistent data throughout linked tables
• Record can be added and removed without any issues
• Complex queries can be carried out

Question 9

What is an index?

Answer 9

Data structure used to look up and access data in database quickly.

Question 10

Is the primary key automatically indexed?

Answer 10

Yes

Question 11

What does capturing data mean?

Answer 11

Process of getting the information you wish to use

Question 12

What method do banks use to capture data from cheques?

Answer 12

They use Magnetic Ink Character Recognition (MICR) to get all the details apart from the amount which must be entered manually.

Question 13

What does selecting data mean?

Answer 13

Process of reducing excess information to obtain only data you require.

Question 14

What does managing the data mean?

Answer 14

To manipulate the information in any type of way such as sorting through it or selecting certain parts using SQL.

Question 15

What is the most common language to manipulate databases in?

Answer 15

SQL

Question 16

What are the requirements to be in First Normal Form (1NF)?

Answer 16

No attribute that contains more than a single value in a cell.

Question 17

What are the requirements to be in Second Normal Form (2NF)?

Answer 17

• Database is in 1NF
• There are no partial key dependencies

Question 18

What are the requirements to be in Third Normal Form (3NF)?

Answer 18

• Database is in 2NF
• There are no non-key dependencies

Question 19

What does SQL stand for?

Answer 19

Structured Query Language

Question 20

What is SQL?

Answer 20

A declarative language used to manipulate databases.

Question 21

What is referential integrity?

Answer 21

Process of ensuring consistency as it makes sure that information is not removed if it’s requires elsewhere in a linked list.

Question 22

What is a transaction defined as?

Answer 22

A single operation executed on data.

Question 23

What does ACID stand for?

Answer 23

• Atomicity
• Consistency
• Isolation
• Durability

Question 24

What does atomicity mean in ACID?

Answer 24

A transaction must be processed in its entirety or not at all.

Question 25

What does consistency mean in ACID?

Answer 25

A transaction must always maintain referential integrity rules between linked tables.

Question 26

What does isolation mean in ACID?

Answer 26

Simultaneous execution of transactions should lead to the same result as if they were executes one after the other.

Question 27

What does durability mean in ACID?

Answer 27

Once a transaction has been executes it will remain so regardless of the circumstances.

Question 28

What is record locking?

Answer 28

Process of preventing simultaneous access to a record.

Question 29

What is the name of an issue that can arise as a result of record locking?

Answer 29

Deadlock

Question 30

What is redundancy?

Answer 30

The process of creating more than one copy of data in a physically different location.