Organisation of Data Flashcards Preview

Computer Science > Organisation of Data > Flashcards

Flashcards in Organisation of Data Deck (22)
Loading flashcards...
1

Field

Part of record designed to hold a single data item of a specified type

2

Record

Collection of items (may be of differing data types) relating to an individual or object

3

Master file

The principal source of data for an application Semi permanent file which contains some data that may change whenever a transaction
occurs

4

Transaction file

data file in which transaction records that relate to entries in a master file are stored

5

Data validation

A check made by the program to ensure the data entered is reasonable

6

Range Check

The computer checks that data must be a value that falls between two predefined values

7

Presence Check

The computer checks that a value must be entered,

8

Format Check

The computer checks that the data must conform to a prescribed layout (specific numbers or letters)

9

Data Type

The computer checks that the data must be of a specific type (number, text, Boolean, etc.)

10

Fixed Value / Drop
down

The computer checks that the data must conform to one of the values in a predefined list

11

Data verification

Checking transferred data by comparing copies of the data before and after transfer to ensure the data are accurate.

12

Double Entry

Normally the user will have to type in twice. Both entries are compared

13

Proof reading

Read before you submit to compare both

14

Serial file

A file that contains data collected in consecutive manner in no particular order (e.g. cashpoint transactions)

15

Sequential file

A file that contains data or records are stored, one after another, in a defined order ( e.g. Class register by surname)

16

Indexed
Sequential

A file that contains data (records) ordered in primary key sequence.
Another file also has an index to allow data to be accessed directly

17

Random access
file

Hashing algorithm is used on key field to calculate the location for the record in the file

18

Header
information

Data stored within the file about the file e.g. file name, file size

19

Fixed length
records

Each record is of the same length (each field in the record has a fixed number of characters)

20

Variable length
records

One or more fields within the record can be of different length

21

A generation file backup system

o This involves storage of three of the most recent
versions of master file. (grandfather – father - son)
o Useful if one version is corrupted: the previous
version(s) is still available.
o Data should

22

Incremental backup

o Only backs up data that has changed and writes
over older back ups
o Useful as it saves storage space and is faster
than full backup
o Only allows the user to restore the most recent
backup.