Database Software

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Database Software

• File Management Systems
• Database Management Systems

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Both Groups Contain

• File Manager
• creating file structure
• adding, deleting, or editing records
• sorting records
• Query Facility
• Report Generator

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File Management Systems

• Work with one file at a time
• Usually cheap and easy to use
• Inefficient for relating data in different files

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Example

• Order File
• customer number
• order

• Customer File
• customer number
• name
• address

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Problems with File Management Systems

• data redundancy - repetition of the same data in
  different files
• data integrity - errors caused by differences in
  redundant data
• data dependence - files are dependent on hardware
  or software

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Database Management Systems

• Can combine information from more than one file
• Self-descriptive
• Expanded query facilities
• nonprocedural query languages
• procedural query languages (SQL)
• Data Security

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Advantages of Database Management Systems

• better information
• faster response time
• lower operating costs
• fewer storage requirements
• improved data integrity
• better data management and security

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Disadvantages of Database Management Systems

• DBMS software is relatively expensive
• often requires new hardware
• usually requires training to use

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Database Management on Large Computer Systems

• Hierarchical
• Network
• Relational
• Object Oriented
• Client Server Systems
• Distributed Database Systems

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Hierarchical Databases

• first to be developed
• stores data in the form of a tree
• sets up a one to many relationship

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Network Databases

• modification of the tree model
• relationship between data elements can be many to
  one or many to many

12
Hierarchical and Network Data Models

• less data redundancy than relational model
• fast data access for predefined queries
• good security
• useful for transaction processing environments
• not very flexible - designed for speed

13
Relational Database Model

• based on tables of data objects
• designed for flexibility
• useful for decision support
• slower processing times and less security than
  other two models

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Object Oriented Database

• Can store objects in a database
• object-relational database management systems
• Oracle, Access

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Client-Server Systems

• Client computers run a desktop DBMS with a GUI
• front end - Access, Paradox
• Server computer contains and manages the database
  itself
• back end - SQL Server, DB2
• Lower hardware cost
• Scalability

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Distributed Database Systems

• database is divided among several smaller
  computers that are hooked up in a client-server
  form of a network
• data is stored at most needed site
• all clients on the network can access any part of
  the database