Database

What is a Database?

•    A large amount of information stored in a computer system

       in such a way that it can be easily looked at or changed.

•  A logically coherent collection of related data that

      (i) describes the entities and their inter-relationships.

     (ii) is designed, built &populated for a specific reason.

• Systematically organized or structured repository of indexed information (usually as a group of linked data files) that allows easy retrieval, updating, analysis, and output of data.
• Stored usually in a computer, this data could be in the form of graphics, reports, scripts, tables etc., representing almost every kind of information.
• Most computer applications (including antivirus software, spreadsheets, word-processors) are databases at their core.
  

Database design methodology

A structured approach that uses procedures, techniques, tools, and documentation aids to support and facilitate the process of design.

=>Conceptual database design

=>Logical database design

=>Physical database design

Database Tables

Tables are the essential component of any database. Without them, you don’t have a database.A table is a collection of rows having one or more columns.The row is the smallest unit of data that can be inserted into a table and deleted from a table. A column name can be used in more than one tables and to maintain the integrity of data and reduce redundancy. This is called a relation.

A database table is composed of records and fields that hold data. Tables are also called datasheets.

Records

Data is stored in records. A record is composed of fields and contains all the data about one particular person, company, or item in a database.

Fields

A field is part of a record and contains a single piece of data for the subject of the record.

Example Uses of Database Systems

–account maintenance & access in banking

-lending library systems

-airline reservation systems

-internet purchasing systems

-media archives for radio/tv stations