Thursday, October 15, 2009

Information Systems and data Bases

This article discuss computer information processing systems and Issues related to data bases
Information systems and databases Information systems
Characteristics of information systems
The creation of information from data is called information processing, data processing or electronic data processing. Data are raw facts and information is data organised in a way that gives the data meaning.
The characteristics of information systems are that they:
  • Organise data to give information
  • Analyse information to give knowledge.
Types of purposes of information system
Information systems can be described as:
  • Transaction processing systems – to record organisations activities.
  • Management information systems – to produce reports about the organisation.
  • Decision support systems – to plan for the future of the organisation
  • Office automation systems – to manage the information used in an organisation.
Examples of database information systems
School Database information system
The Environment of a school database information system would include:
  • The school community
  • The educational services
  • The hardware and software
The purpose of a school database administration system is to maintain the efficient operation of the school, its personnel, finances, resources and administrative tasks.
Data could include:
  • Equipment register
  • Finance and purchase orders
  • GST records
  • Student marks and grades
  • Student personal and academic information
Participants are those people who directly use the information system. Everyone involved in a school is likely to be a system participant at some stage.
Most data entry and access in a school information system is through the keyboard and monitor. Typical hard copy outputs include class lists, daily absentee lists, order forms and financial statements.
Basic data organisation methods
Manual organising methods
Manual information systems have been in use for millennia.
Manual information systems often need duplicate sets of all the data.
Computer-based organising methods
Computerised information systems provide greater flexibility.
Flat file database management systems
Flat file database management systems are the easiest to learn and use.
Relational database management systems
DBMS is the standard abbreviation for a database management system.
Hypermedia systems
Hypermedia is any display object that will link you to new information. Hypertext is a ‘text only’ form of hypermedia.
Organisation of data in databases
The logical organisation of a flat file database
The structure of a flat file database is:
  • Database
  • File
  • Record
  • Field, key field
  • Character
An entity is a specific thing about which an information system collects and processes data. In a database of students, each student is an entity.
The key field contains data that is unique to each record. It is like a ‘fingerprint’ that identifies each record in a database.
The logical organisation of a relational database
A relationship is a table or file created by joining together data from different databases.
An attribute is a field copied from a parent database. Attributes are the columns in a relationship table shown in list view.
A calculated field is a field that is created by a calculation using data taken from other fields.
Records in a relationship are sometimes called ‘tuples’.
Relationships can be saved as new database files.
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