Topic 10 - Fundamentals of databases - Complete

Question 1

Define database?

Answer 1

Is a persistent organised store of data that is used on a computer system

Question 2

Define flat-file database?

Answer 2

Can be created in a word processor or spreadsheet
Is composed of 1 file or table.
Each row is a record, each column is a field.

Question 3

Define relational database?

Answer 3

Is where data is contained in more than one table. Tables are then joined by linking a primary key in one table to a foreign key in another table.

Question 4

Define primary key?

Answer 4

Is a unique identifier such as a code number that can be used to identify each record in a database table.

Question 5

Define foreign key

Answer 5

Is a field in a table which can be linked to a primary key of another table.

Question 6

Define composite key?

Answer 6

Is used in a table where two columns are used to form a combined key field. Both columns combined make a unique reference.

Question 7

Define entity?

Answer 7

Is an object that we store data about, such as a customer or a product. It becomes a table in a database.

Question 8

Define attributes?

Answer 8

Are the details about an entity.

Question 9

Define data redundancy?

Answer 9

Linking data tables can reduce the duplication of data.

Question 10

Define normalisation in a database?

Answer 10

Is the formal process involved in the design of an efficient database, this is a multi-staged process where tables are created to cause a reduction in the data dependency

Question 11

Define the first, second and third normal form?

Answer 11

Is where the tables contain NO:
1st - repeating attributes or groups of attributes.
2nd - partial key dependencies.
3rd - non-key dependencies.

Question 12

Define client-server databases model?

Answer 12

User’s who accesses the database from one of many workstations on the network.

The database installed and maintained on a server and the client is a user on a workstation.

Question 13

Define DBMS (Database management system)?

Answer 13

Is a software application designed to:

• Interact with database users
• Capture, extract and analyse the data
• Interact with other software applications.

Question 14

Define tables in DBMS?

Answer 14

Are used to store data which can be captured by a data entry form.

Question 15

Define queries in DBMS?

Answer 15

Used to retrieve specific data from a table, where this data is stored in more than one table a complex query will process the data into a single datasheet.

Question 16

Define reports in DBMS?

Answer 16

Used to summarise and present the data that is in tables, a report is usually required for a specific issue.

Question 17

Define DBMS and administration?

Answer 17

DBMS software is used by the database administrator to maintain the system.

• Provides for a centralised automatic backup of the system.
• Assign different types of database user with associated access rights.
• Provide login and password facilities for users.
• Update of DBMS programs and development of associated software tools.

Question 18

Define program-data independence?

Answer 18

In a DBMS the data is separated from the applications that access it, so programs work independently of the data.

Question 19

Define record locking in client-server databases?

Answer 19

A record is locked when it is being accessed by a user with write access, this prevents additional users from editing and saving the record until the original user has completed their database transaction.

Question 20

Define serialisation in client-server databases?

Answer 20

This technique only permits one transaction at a time to take place when multiple users are updating a database.

Question 21

Define timestamp ordering in client-server databases?

Answer 21

Timestamps the start time of each database transaction that takes place based on the system clock. The oldest timestamp transaction takes priority and is executed first where multiple transactions take place on the same record.

Question 22

Define commitment ordering in client-server databases?

Answer 22

The order of operation of concurrent transactions is based on the timestamp and the precedence of the particular command requested.