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
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.
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.
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
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