Database Management
Systems
Introduction
Pınar Yıldırım
Database management systems
• Database: organized collection of logically related data
• Data: stored representations of meaningful objects and events (numbers, texts, images etc.)
• Information: data processed to increase knowledge in the person using the data
• Metadata: data that describes the properties and context of user data
• Data example for class
Course: MGT 500 Business Policy
Semester: Spring 2010
Section: 2
Meta data for class
Name Type Length
Name ID GPA Course Alphanumeric 30
Section Integer 1
John 34 2.9
Semester Alphanumeric 10
Lewis 53 3.4 Name Alphanumeric 25
ID Integer 2
Jane 40 2.7
GPA Decimal 3
Disadvantages of file processing (without database)
• Program-data dependence
• Duplication of data (different systems/programs have separate copies of the same data)
• Limited data sharing (No centralized control of data)
• Lengthy development times(Programmers must design their own file formats)
• Excessive program maintenance
Duplicate data
Problems
• Programmers should maintain their own data.
• Application programs need to contain code for the metadata of files.
• Each application program must have its own. processing for reading,
inserting, updating etc.
• Lack of central control
• There is no standard file format.
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Problems with data redundancy
• Waste of space to have duplicate data
• Causes more maintenance problems
• The biggest problem
• Data changes in one file could cause inconsistencies
• Data integrity
•
Solution the database approach
• Central respository of shared data
• Stored in a standardized, convenient form
• Requires a database management system (RDMS)
Database Management System
A software system that is used to create, maintain and provide controlled access
to user database.
Components of Database Management Systems
Advantages of the database approach
• Program-data independence
• Planned data redundancy
• Improved data consistency
• Improved data quality
• Improved data accessibility
• Reduced program maintenance
Costs and risks of the database approach
• Specialized personnel
• Installation and management cost and complexity
• Need for backup and recovery
People involved
• Systems analysts
• Database analysts and data modellers
• Users
• Programmers
• Database administrators
People Involved
Parts of the Database Environment
• Repository–centralized storehouse of metadata
• Database Management System (DBMS) –software for managing the
database
• Database–storehouse of the data
• Application Programs–software using the data
• User Interface–text and graphical displays to users
• Data/Database Administrators–people responsible for maintaining the
database
• System Developers–people responsible for designing databases and
software
• End Users–people who use the applications and databases
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Evolution of database systems
• Need for program-day independence
• Desire to manage more complex data types and structures
• Ease of data access
• Need for more powerful decision support platforms
Evolution of database systems
• Flat files
• Hierarchical
• Network
• Relational
• Object-oriented
• …
Evolution of database systems
Two-tier database with local area network
Three-tiered client/server database architecture
Enterprise data model
• Specifies scope and general context
• Entity-relationship diagrams
• Descriptions of entity types
• Relationships between entities
System Development Life Cycle
System Development Life Cycle
• Planning:
• Preliminary understanding
• Request for study
• Analysis:
• Thorough requirements analysis and structuring
• Functional system specifications
• Logical Design:
• Information requirements elicitation and structure
• Detailed design specifications
System Development Life Cycle
• Physical Design:
• Develop technology and organizational specifications
• Program/data structures, technology purchases, organization redesigns
• Implementation:
• Programming, testing, training, installation, documenting
• Operational programs, documentation, training materials
• Maintenance:
• Purpose–monitor, repair, enhance
• Deliverable–periodic audits
References
• Modern Database Management 11th Edition, Jeffrey A. Hoffer, V. Ramesh, Heikki Topi © 2013
Pearson Education, Inc. Publishing as Prentice Hall
