A451: Topic 5 - Databases

Question 1

A database is a persistent store of data. What does persistent mean?

Answer 1

Once data is put into the database it is stored and can be accessed again later.

Question 2

What is database software used for?

Answer 2

To interrogate the database – asking ‘questions’ which brings up results.
To create a new database.
To update data in a database.

Question 3

The data must also be stored in an …………. way so that items can be easily found.

Answer 3

Organised

Question 4

Software that helps us to create and use computer databases is called data ………….. Software

Answer 4

Handling

Question 5

This software helps us to ……….. the data to find the items we need and also to ………… if any of the data changes.

Answer 5

Interrogate, update

Question 6

Define a database?

Answer 6

A database is a persistent collection of data or information which is held together in an organised way.

Question 7

Examples of where databases are used?

Answer 7

• Search engines

- School Registers

Question 8

Describe what is meant by a table?

Answer 8

A display where data is arranged in fields and Records that are ordered and organised.

Question 9

Describe what is meant by a field?

Answer 9

A peace of data or attribute part of a record, the data is of a specific type.

Question 10

Describe what is meant by record?

Answer 10

Collection of items of many data types or fields that relate to one record or object.

Question 11

Describe what is meant by a query?

Answer 11

Rules that need to be satisfied when searching for data.

Question 12

Example of a query?

Answer 12

Age < 14 AND Gender = ‘M’

Question 13

What is data validation?

Answer 13

Ensures data entered complies with rules set, this is only the computer performing a task.

Question 14

What is data Verification?

Answer 14

Ways of checking for accuracy, examples include making the user enter e-mail address twice and comparing to check it is correct.

Question 15

Define DBMS?

Answer 15

Data Base Management System.

Question 16

Benefits of storing a database on a central server?

Answer 16

• Easier to keep secure.

- Users can choose which piece of client software to access the data with

Question 17

Software used by individual supermarkets to access the single central database is called ………. software.

Answer 17

client

Question 18

Using a DBMS, the data is stored in a ……….. way which can then be accessed using different …………. software.

Answer 18

standard, client

Question 19

The DBMS also allows the user to build …………. for easier, more user-friendly, data entry.

Answer 19

forms

Question 20

The results of searches can be combined into ……… for more readable and informative printouts.

Answer 20

reports

Question 21

What is not a simple attribute name?

Answer 21

Personal Details

Question 22

We use a primary key because each key in a table needs to be:

Answer 22

unique.

Question 23

Example of a parameter?

Answer 23

last_name=’Smith’

Question 24

What is a Primary Key?

Answer 24

When we design a database we have a special field in each table which ensures every record in the table is uniquely identifiable. This field is called the:

Question 25

Why do we need data handling software in a database?

Answer 25

This is so that data can be store in the correct way and found in the correct way. Update information inn the correct name and interrogate the data base in the correct way.

Question 26

Define Entity?

Answer 26

A thing we are storing data about.

Question 27

Example of Entity or Table?

Answer 27

Student.

Question 28

Example of Attributes or Fields?

Answer 28

Gender

Question 29

-------------<- =

Answer 29

one to many

Question 30

--------------- =

Answer 30

one to one

Question 31

->----------<- =

Answer 31

many to many

Question 32

Three databases which may hold information about you?

Answer 32

- Hospital database - government database - school database.

Question 33

List three database functions of the software assist you with?

Answer 33

- interrogating the database to find data. - editing information on the database. - creating new database.

Question 34

Describe the features of a DBMS that can be used to create data handling applications?

Answer 34

- Provides a set of tools for accessing/maintaining the database, e.g. to define/create tables, run queries or define reports. - The application is independent from the database itself. - Provides data integrity control (e.g. integrity checks, validation checks). - Controls access to data, including security and multiple user access.

Question 35

Explain the advantages of using a DBMS.

Answer 35

- Features can be set up beforehand by an expert and used by an end user. - Separating application and database means the database can be accessed separately by other means e.g. a desktop application and web application accessing the same data/other suitable example.

Question 36

What are attributes?

Answer 36

- Attributes are the set of properties used to describe instances of the entity. It is an item of data that can be stored about the entity.

Question 37

Benefits of separating the data from the applicants in a database?

Answer 37

- Multiple platforms or applications they are able to separate on the same data. it censures no redundancy between applications.

Question 38

Explain what is meant by a entity and how entities relate to the tables. (4)

Answer 38

• An entity is a type of real world object (about which data is to be stored) • e.g. Songs/albums/singers etc • In the relational database each entity is modelled as a table • Instances/examples/individuals of an entity are represented by records/rows of the table • Entities can have attributes • .. valid example of attributes e.g. length of song • Attributes of an entity are represented by fields/columns of the table

Question 39

What is meant by selection?

Answer 39

A condition is used to decide whether code should be executed.

Question 40

What is meant by iteration?

Answer 40

code is executed repeatedly.