Databases

Question 1

What does Referential Integrity mean?

Answer 1

Prevents you from deleting related records

Question 2

What is a serial file?

Answer 2

Permanent storage of data

• Data is in the order at which it was entered
• No order to the data is maintained

Question 3

What is a sequential file?

Answer 3

• Data stored in order of a key field

- The order is maintained when new records are added

Question 4

What is an indexed sequential file?

Answer 4

Maintain an index to allow groups of records to be accessed quickly.

Question 5

What is a database?

Answer 5

A database is a structured, persistent collection of data

Question 6

What are the advantages of using a database?

Answer 6

• Makes processing more efficient
• Reduces storage requirements
• Avoid redundancy
• Allows different users to only see relevant data

Question 7

What is a DBMS?

Answer 7

Software which manages the database

Question 8

What features does a DBMS provide?

Answer 8

• A manipulation language to access and change the data
• Integrity to ensure efficiency and structure is not compromised
• Additional security
• An interface for other programs to access and use the data
• Programs/data independence

Question 9

What are the components of a database?

Answer 9

• Tables that store data in rows and columns
• Queries to manipulate data
• Forms or user interface
• Reports

Question 10

What is a flat file?

Answer 10

One table and all data is stored within it.

Question 11

What are the disadvantages of a flat file?

Answer 11

• Inefficient as it is not easy to query
• Data is duplicated (redundancy) inefficient use of storage. Errors can occur between different records easily and integrity is compromised.

Question 12

What is a relational database?

Answer 12

A relational database has more than one related table.

Question 13

How do you get from a flat file to a relational database?

Answer 13

Normalisation

Question 14

What must be true for a relational database?

Answer 14

• Each record must be unique, primary key is unique identifier for the record.

Question 15

What is a foreign key?

Answer 15

A field in one table that uniquely identifiers a row of another table or the same table.

Question 16

What are the types of relationship?

Answer 16

• One to One
• One to Many
• You cannot design a database with Many to Many relationships

Question 17

What is the primary key also known as and what is it used for?

Answer 17

Index used to quickly find records.

Question 18

What are secondary keys used for?

Answer 18

To quickly perform query’s on the database.