Organisation of Data Flashcards
Field
Part of record designed to hold a single data item of a specified type
Record
Collection of items (may be of differing data types) relating to an individual or object
Master file
The principal source of data for an application Semi permanent file which contains some data that may change whenever a transaction
occurs
Transaction file
data file in which transaction records that relate to entries in a master file are stored
Data validation
A check made by the program to ensure the data entered is reasonable
Range Check
The computer checks that data must be a value that falls between two predefined values
Presence Check
The computer checks that a value must be entered,
Format Check
The computer checks that the data must conform to a prescribed layout (specific numbers or letters)
Data Type
The computer checks that the data must be of a specific type (number, text, Boolean, etc.)
Fixed Value / Drop
down
The computer checks that the data must conform to one of the values in a predefined list
Data verification
Checking transferred data by comparing copies of the data before and after transfer to ensure the data are accurate.
Double Entry
Normally the user will have to type in twice. Both entries are compared
Proof reading
Read before you submit to compare both
Serial file
A file that contains data collected in consecutive manner in no particular order (e.g. cashpoint transactions)
Sequential file
A file that contains data or records are stored, one after another, in a defined order ( e.g. Class register by surname)
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
Random access
file
Hashing algorithm is used on key field to calculate the location for the record in the file
Header
information
Data stored within the file about the file e.g. file name, file size
Fixed length
records
Each record is of the same length (each field in the record has a fixed number of characters)
Variable length
records
One or more fields within the record can be of different length
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
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.
