Database System Terminologies

TERMINOLOGY

Database

o  Collection of related data (logically coherent)

o Known facts that can be recorded and that have implicit meaning o Represents some aspect(s) of the real world (miniworld)

o Built for a specific purpose Examples of large databases

 •Amazon.com, Canadian Census, The Bay‟s product inventory, data collection underlying Quest

Database management system  (DBMS)

Collection of programs

Enables users to create and maintain a database

Allows multiple users and programs to access and manipulate the database concurrently Provides protection against unauthorized access and manipulation

Provides means to evolve database and program behaviour as requirements change over

time

Examples of database management systems

IBM‟s DB2, Microsoft‟s Access and SQL Server, Oracle, MySQL, SAP‟s SQL

Anywhere

Defining a database

Specifying the data types, structures, and constraints of the data to be stored

Uses a Data Definition Language

Meta-data

Database definition or descriptive information

Stored by the DBMS in the form of a database catalog or data dictionary

Phases for designing a database:

Requirements specification and analysis

Conceptual design

e.g., using the Entity-Relationship model

Logical design

e.g., using the relational model

Physical design

Populating a database

Inserting data to reflect the miniworld

Query

Interaction causing some data to be retrieved

uses a Query Language

Manipulating a database

Querying and updating the database to understand/reflect miniworld

Generating reports

Uses a Data Manipulation Language

Application program

Accesses database by sending queries and updates to DBMS

Transaction

An atomic unit of queries and updates that must be executed as a whole e.g., buying a product, transferring funds, switching co-op streams