Unit 5

Question 1

1. What is the relationship between database and information systems?

Answer 1

Database is a collection of records. Information Systems maintain and access transactional data in the database.

Data should be stored and managed efficiently in electronic storage devices, which is the need a database fulfils.

Question 2

2. What are the problems of non-database systems?

Answer 2

Data redundancy, data inconsistency, and data isolation.

Question 3

3. What is the relationship between database and DBMS?

Answer 3

Database Management Systems (DBMS) is the software used to:

• reduce redundancy
• share data
• reduce data integrity problem

DBMS is used to interact with a database - to create, manage, maintain, and manipulate a database.

Question 4

4. What are the benefits of DBMS?

Answer 4

Data security, data integrity, and data independence.

Question 5

5. What are the characteristics of a relational database?

Answer 5

A database structured to recognise relations among stored items of information.

Data hierarchy from a logical view: fields (columns), records (rows), file (table) and a database. Each table must have a primary key that uniquely identifies each row (record).
A primary key can be either a composite primary key (consisting of more than one field, e.g. building no. and room no.) and an atomic primary key (consisting of only one field). A foreign key is an attribute in a child table that reference a primary key of a parent table.

Question 6

What is the main purpose of normalisation of a database?

Answer 6

To reduce data redundancy and hence the duplication of data.

Question 7

7. What is the relationship between tables in a database and forms?

Answer 7

Database forms provide an interface for entering and displaying data while a table is merely a file for some specific purpose, e.g. customer file. Therefore, a form is the interface used to gather data in a specific file (table).

Question 8

8. What is the relationship between database queries and forms?

Answer 8

A query is an inquiry into a database used to extract (select) data from the database in a readable format. So, a database query can extract data from files in a database. A database query is more sophisticated than a database form.