Chapter 5 - Databases Flashcards

1
Q

Database

A

Persistent (saved on secondary storage) organised store of data

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2
Q

Data integrity

A

Data reflecting reality

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3
Q

Validation

A

The process of checking data through software when it is input

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4
Q

Verification

A

Checking that the data entered is correct with duplicate file

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5
Q

Data matching

A

Compares different databases to look for particular relationships

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6
Q

Data mining

A

Looks in many different unrelated databases

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7
Q

Flat file database

A

Just rows (records) and columns (fields) - only 1 table

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8
Q

Data redundancy

A

Unnecessarily storing data in several places (repetition)

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9
Q

Relational databases

A

Stores data in separate tables which are linked on key fields

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10
Q

Entity

A

Something in real life about which data can be stored

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11
Q

DBMS

A

Database Management System is software that creates and manages a database and separates data from applications to minimise data redundancy

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12
Q

Transactions

A

A change in a database - must not damage data integrity

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13
Q

Record locking

A

Allows only one person to edit data at one time

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14
Q

Primary key

A

Unique identifier of a record which can be linked to a foreign key from another table

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15
Q

Forms

A

Provide a user friendly interface for data input or output

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16
Q

Reports

A

Physical outputs from a database

17
Q

Queries

A

Used to extract data (using either a graphical interface or SQL (structured query language))

18
Q

Modules

A

Units of software that take care of a particular function

19
Q

What do databases need to be? (4)

A

1) Accurate
2) Up to date
3) Available
4) Protected

20
Q

What do databases need to be protected against? (5)

A

1) Errors
2) Loss
3) Insufficient data
4) Inconsistencies
5) Unauthorised access

21
Q

How can data be lost? (3)

A

1) Catastrophes e.g. flood
2) Accidental deletion
3) Malicious action

22
Q

How can database problems be avoided? (4)

A

1) Validation
2) Frequent back ups
3) Locking action
4) Access levels

23
Q

What do most people need to do to a database?

A

Create
Read
Update
Delete

24
Q

What are the disadvantages of flat file databases? (2)

A

1) Very limited

2) Data redundancy - inconsistent updates

25
What does a DBMS do? (4)
1) Creates database applications 2) Protects data 3) Runs queries 4) Keeps data consistent and accurate
26
Why does data need to separated from applications? (4)
1) Programmers do not have to worry about damaging data 2) Applications can be written without restructuring data 3) Data easily shared between applications 4) Only one copy of data - no redundancy
27
What are the main features of a DBMS? (7)
1) Record locking 2) Creating tables 3) Graphs 4) Queries 5) Validation 6) Security 7) Automatic backups
28
Why are data types used?
Makes it easier for software to validate and process data, and decisions about space allocation can be made
29
What is a range check?
Checking if value entered fits into pre-determined range, data falls between two extreme values
30
What is a check digit?
Extra digit added to data produced by an algorithm