A database is a
collection of information that is organized so that it can easily be accessed,
managed, and updated. In one view, databases can be classified according to types
of content: bibliographic, full-text, numeric, and images.
Within a computer's storage, data is a collection
of numbers represented as bytes that are in turn composed of bits (binary
digits) that can have the value one or zero. Data are processed by
the CPU, which uses logical operations to produce new data(out) from source input.
Information is stimuli that has meaning in some context for
its receiver. When information is entered into and stored in a computer, it is generally referred to as data. After processing
(such as formatting and printing), output data can again be perceived as information.
Database software, often called a database
management system (DBMS) allows
users to
:-
· Create a computerized database
· Add, modify and delete data
· Sort and retrieve data
· Create form and report form data
Data integrity identifies
the quality of the data
Garbage in, garbage out
(GIGO) points out the accuracy of a computer’s output depends on the accuracy
of the input.
Valuable information should
have following characterstic :-
- · Accurate
- · Verifiable
- · Timely
- · Organized
- · Accessibility
- · Useful
- · Cost effective
A character is one byte.
Numbers, letters, space, punctuation marks, or other
symbols.
A field is a combination of one or more related characters
- · Field name
- · Field size
- · Data type
4
layers of data hierarchy :-
- · Character
- · Field
- · Record
- · Files
A record is a group of related fields.
A primary key
uniquely identifies each record. When
a record no longer is needed, a user deletes it from a file.
A data file is a collection of related records. A data
dictionary contains data about each file in the database and each field
in those files.
A query language consists of simple, English-like statements that
allow users to specify the data to display, print, or store.
Query by example (QBE) provides a GUI to assist users with retrieving data.
A report generator allows users to design a report on the screen,
retrieve data into the report design, and then display or print the report.
A DBMS provides means to ensure that only authorized users access data at permitted times. A DMBS provides a variety of technique to restore the database to a usable form in case it is damaged or destroyed :-
- · Backup
- · Log
- · Recovery utility
- · Continuous backup
A data model
consists of rules and standards that define how the database organizes data. A relational
database stores data in tables
that consist of rows and columns. A relationship
is a link within the data
- · Each row has a primary key
- · Each column has a unique name
An object-oriented
database (OODB) stores
data in objects. Examples
of applications appropriate for an object-oriented database include:-
- · Multimedia database
- · Groupware database
- · Computer aided database
- · Hypertext database
A multidimensional database can store data in more than two
dimensions of data.
·
Sometimes known as a hypercube.
·
Can consolidate data much faster than a relational
database.
A data warehouse is a huge database that stores and manages the data
required to analyze historical and current transactions.
Databases on the web allow
you to :-
- · Shop for product –amazon, ebay, zalora, 11 street
- · Buy and sell stock –Job street , Mudha
- · Object oriented – google map
- · Search for job
- · Make airline reservation- South Africa Airways
- · Register for college class
- · Check semester grades
Employees should learn how to use the data in the
database effectively :-
·
Interact with database
·
Identify new data for the database
·
Maintain the database
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