DATA STRUCTURES
ORGANISATION OF DATA
Characters, facts, records, files and databases form an organisation of data. The basic building
block of data is a character. The character consists of upper and lower-case letter, numeric digits
or symbols. Upper and lower-case letters are Aa, Bb, Cc,… Zz. Numeric digits are 0, 1, 2,..,9.
Symbols involve commas (,) quotation mark (?) plus (+) division (/) and so on. Upper and lowercase
letters are called alphabetic character. Numeric digits are called numeric character. Symbol
is called special characters. A combination of the three types is called alphanumeric characters
(#2B, N2.50K). A computer can accept both alphanumeric and numeric and store them in
memory.
Characters are put together to form a fact. A fact is also called a field. A fact or field is a number,
an item, word, name or a combination of characters. Facts are put together to form a record. A
record is a related items of data in a file. An employee record in a company would be a collection
of facts about one employee. Their facts would include the employee’s name, address,
department, phone number, position, pay rate, earning made to date etc.
Records are combined together to make a file. A collection of related records is a file. E.g. A
collection of all employee records for one company would be an employee file. Files are
combined together to make a database. The heart of most computer processing is data. An
organisation uses data as raw materials to be stored in database. Once the data have been
processed, they are called information.
TYPES OF DATA
There are two types of data - Numeric data and alphanumeric data. Numeric data is expressed in
numbers e.g. age is 35; date of birth is 1970. Numeric data contain only numeric characters or
numbers.
Alphanumeric data is composed of combination of letters, numbers or special punctuation
character e.g.
Name = Abeokuta
Address = 17, Ibadan Road
Date = 26th October, 2000
STRUCTURE OF THE DATA
The structure of the data is the composition of records into files for generating information. Let
us take an example of long-distance telephone call, the following items of data are recorded:
. Telephone number of the person to whom the call is to be billed
. Telephone number of the person receiving the call
. Duration of the call in minutes
. Time that call is placed
. Type of call e.g. person-to-person or station-to-station.
These data need processing for generating bill information.
Description – Long-distance telephone call data
Field Names Types of data Number of Character
Phone no to be billed
Phone no of call receiver
Duration of call
Time call is placed
Type of call