A451: Topic 5 - Databases Flashcards Preview

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Flashcards in A451: Topic 5 - Databases Deck (40)
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1
Q

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

A

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

2
Q

What is database software used for?

A

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

3
Q

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

A

Organised

4
Q

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

A

Handling

5
Q

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

A

Interrogate, update

6
Q

Define a database?

A

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

7
Q

Examples of where databases are used?

A
  • Search engines

- School Registers

8
Q

Describe what is meant by a table?

A

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

9
Q

Describe what is meant by a field?

A

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

10
Q

Describe what is meant by record?

A

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

11
Q

Describe what is meant by a query?

A

Rules that need to be satisfied when searching for data.

12
Q

Example of a query?

A

Age < 14 AND Gender = ‘M’

13
Q

What is data validation?

A

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

14
Q

What is data Verification?

A

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

15
Q

Define DBMS?

A

Data Base Management System.

16
Q

Benefits of storing a database on a central server?

A
  • Easier to keep secure.

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

17
Q

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

A

client

18
Q

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

A

standard, client

19
Q

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

A

forms

20
Q

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

A

reports

21
Q

What is not a simple attribute name?

A

Personal Details

22
Q

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

A

unique.

23
Q

Example of a parameter?

A

last_name=’Smith’

24
Q

What is a Primary Key?

A

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:

25
Q

Why do we need data handling software in a database?

A

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.

26
Q

Define Entity?

A

A thing we are storing data about.

27
Q

Example of Entity or Table?

A

Student.

28
Q

Example of Attributes or Fields?

A

Gender

29
Q

————-<- =

A

one to many

30
Q

————— =

A

one to one

31
Q

->———-<- =

A

many to many

32
Q

Three databases which may hold information about you?

A
  • Hospital database
  • government database
  • school database.
33
Q

List three database functions of the software assist you with?

A
  • interrogating the database to find data.
  • editing information on the database.
  • creating new database.
34
Q

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

A
  • 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.
35
Q

Explain the advantages of using a DBMS.

A
  • 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.
36
Q

What are attributes?

A
  • 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.
37
Q

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

A
  • Multiple platforms or applications
    they are able to separate on the same data.
    it censures no redundancy between applications.
38
Q

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

A

• 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

39
Q

What is meant by selection?

A

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

40
Q

What is meant by iteration?

A

code is executed repeatedly.