Supermarket

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WELCOME
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EXAMPLE INFORMATION SYSTEMS

• Supermarket
• Credit card
• Travel agent
• Library
• Insurance
• Universities

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File-based system a collection of application
programs that perform services for the end-users
such as the production of reports. Each program
defines and manages its own data

• Separation and isolation of data
• Duplication of data
• Data dependence
• Incompatible file formats
• Fixed queries/proliferation of application
  programs

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Database a shared collection of logically
related data (and a description of this data),
designed to meet the information needs of an
organization.

• Program-data independence
• System catalog, data dictionary, meta-data
• Entity a distinct object in the organization
• Attribute a property that describes some aspect
  of the object.
• Relationship an association between several
  entities.

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DBMS A software system that enables users to
define, create, and maintain the database and
provides controlled access to this database.

• Data Definition Language (DDL)
• Data Manipulation Language (DML)
• Utilities security, integrity, concurrency,
  recovery
• View mechanism

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Components of the DBMS Environment

• Hardware backend vs. front end
• Software DBMS vs. application programs
• Data operational vs. meta data
• Procedures DBMS maintenance
• People DA, DBA, database designers, application
  programmers, and end-users

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Advantages of DBMS

• Control of data redundancy
• Data consistency and integrity
• Improved security, backup and recovery services,
  maintenance through data independence, data
  accessibility and responsiveness.
• Increased productivity and concurrency

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Disadvantages of DBMS

• Complexity
• Performance
• Cost of DBMS
• Cost of additional hardware
• Cost of conversion
• High impact of a failure