Database Management Systems

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Chapter 4

• Database Management Systems

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What is a DatabaseManagement System (DBMS)?

• Database
• An organized collection of related data
• Database Management System
• Comprises programs to store, retrieve, and
  otherwise manage a computerized database and to
  provide interfaces to application programs and to
  non-programming users

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Functions of A Database Management System

• Storing and Retrieving Data
• The database sees the physical view of the data
• How the data are compressed and formatted, which
  data are stored near each other, and which
  indexes are created to simplify and speed finding
  data on the storage medium

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Functions of A Database Management System
Functions of A Database Management System

• Storing and Retrieving Data
• The database presents a logical view to the user
  and programmer
• Organizes and presents data elements in ways that
  managers and other users find helpful

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Functions of A Database Management System
Functions of A Database Management System

• Managing Metadata
• Metadata are data about data in the database
• Example
• The fact that a company's invoice numbers are six
  digits long, with the first digit being either a
  1 or 3

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Functions of A Database Management System
Functions of A Database Management System

• Limiting and Controlling Redundant Data in
  Multiple Systems
• Companies often collect and store the same data
  in two or more different information systems

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Functions of A Database Management System
Functions of A Database Management System

• Supporting Simultaneous Data Sharing
• Concurrency control
• Describes the proper management of simultaneous
  attempts to update a database by multiple users
  or multiple software programs

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Functions of A Database Management System
Functions of A Database Management System

• Providing Transaction Atomicity
• The concept that a transaction cannot be split
  into smaller parts
• If systems fails in midst of transaction, system
  is restored as if the entire transaction
  completed or no part of it completed

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Functions of A Database Management System
Functions of A Database Management System

• Providing Backup and Recovery Services
• Databases cannot be backed up like files because
  they are too large and in constant use
• Backup techniques include
• Operating in parallel on two storage devices
• Use of temporary database during backup

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Functions of A Database Management System

• Providing Authorization and Security Services
• Most DBMSs can limit who has access to specific
  data
• DBMS can create limited views of data so that
  users can see only what they are authorized to see

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Functions of A Database Management System

• Enforcing Business Rules
• A DBMS enforces rules that ensure related data
  are logically consistent

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Database Applications

• Support for Application Software
• Providing a common data repository
• Performing support functions, such as data
  storage, metadata storage, concurrency control,
  and other DBMS functions that would otherwise
  have to be performed by the application software

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Database Applications

• Data Warehouse
• An enterprise-wide database designed to support
  business intelligence and management decision
  making rather than operational needs

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Database Applications

• Data Mart
• Provides summary and historical data for business
  intelligence and decision making for a single
  department or division rather than an entire
  organization

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Database Applications

• Serving Dynamic Web Pages
• Allows Web content managers to change Web pages
  by updating a database
• Content management
• Software designed to ease the development of Web
  pages by fields from a database into a Web page
  template

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Developing Databases through Data Design

• Data Design
• The process of identifying and formalizing the
  relationships among the elements of data that
  will form an organization's database

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Developing Databases through Data Design
Insert Figure 4-4 here
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Developing Databases through Data Design

• Entity-Relationship (E/R) Model
• The E/R model offers a pictorial way of showing
  the interrelationships among various types of
  data

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The Entity-Relationship Model
Figure 4-5
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Technological Underpinnings

• Distribution Architecture
• Refers to how the organization distributes data
  and database processing physically among the
  computers in a network

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Technological Underpinnings

• Types of Distribution Architectures
• Decentralized architecture
• Involves no data sharing
• Centralized architecture
• Has a single DBMS running on a single computer
  and maintaining data centrally

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Technological Underpinnings

• Types of Distribution Architectures
• Client/Server architecture
• Divides the functions of a DBMS among connected
  computers on a network, while centralizing
  permanent storage for all data on a computer
  called the database server

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Technological Underpinnings

• Types of Distribution Architectures
• Distributed architecture
• Distributes both data and processing
• Treats data as a single database, giving every
  database client and every server access to all
  the data in the database no matter where it
  resides
• Mixed architecture
• Utilizes more than one architecture

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Technological Underpinnings

• Database Models
• Relational model
• A table represents a file with rows called tuples
  and columns called attributes

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Technological Underpinnings
Insert Figure 4-8 here
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Technological Underpinnings

• Database Models
• Object model
• Derives from object-oriented programming
• Object-oriented DBMSs store objects and
  object-class metadata

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Technological Underpinnings

• Database Models
• XML model
• A language used to mark and identify components
  of Web-based transaction documents

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Technological Underpinnings

• Database Models
• Network model
• Builds a tighter linkage between elements of data
• Hierarchical model
• A precursor to the network model, as a network
  model with additional restrictions
• Views data as organized in a logical hierarchy

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Managing the Data Resource

• Data Administrator
• Concerned with integrity of data, data
  redundancy, access controls, and rules about data
  relationships
• Database Administrator (DBA)
• Oversees functioning of particular DBMS
• More technical than data administrator

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End of Chapter 4

• Database Management Systems