Database 1

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Database Systems Design, Implementation, and Management

Coronel | Morris

11e

©2015 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

Chapter 1

Database Systems

©2015 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

Learning Objectives

  • In this chapter, you will learn:
  • The difference between data and information
  • What a database is, the various types of databases, and why they are valuable assets for decision making
  • The importance of database design
  • How modern databases evolved from file systems

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©2015 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

Learning Objectives

  • In this chapter, you will learn:
  • About flaws in file system data management
  • The main components of the database system
  • The main functions of a database management system (DBMS)

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©2015 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

Data vs. Information

Data

Information

  • Raw facts
  • Raw data - Not yet been processed to reveal the meaning
  • Building blocks of information
  • Data management
  • Generation, storage, and retrieval of data
  • Produced by processing data
  • Reveals the meaning of data
  • Enables knowledge creation
  • Should be accurate, relevant, and timely to enable good decision making

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©2015 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

Database

  • Shared, integrated computer structure that stores a collection of:
  • End-user data - Raw facts of interest to end user
  • Metadata: Data about data, which the end-user data are integrated and managed
  • Describe data characteristics and relationships
  • Database management system (DBMS)
  • Collection of programs
  • Manages the database structure
  • Controls access to data stored in the database

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©2015 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

Role of the DBMS

  • Intermediary between the user and the database
  • Enables data to be shared
  • Presents the end user with an integrated view of the data
  • Receives and translates application requests into operations required to fulfill the requests
  • Hides database’s internal complexity from the application programs and users

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©2015 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

Figure 1.2 - The DBMS Manages the Interaction between the End User and the Database

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©2015 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

Advantages of the DBMS

Better data integration and less data inconsistency

Data inconsistency: Different versions of the same data appear in different places

Increased end-user productivity

Improved:

  • Data sharing
  • Data security
  • Data access
  • Decision making
  • Data quality: Promoting accuracy, validity, and timeliness of data

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©2015 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

Types of Databases

  • Single-user database: Supports one user at a time
  • Desktop database: Runs on PC
  • Multiuser database: Supports multiple users at the same time
  • Workgroup databases: Supports a small number of users or a specific department
  • Enterprise database: Supports many users across many departments

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©2015 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

Types of Databases

  • Centralized database: Data is located at a single site
  • Distributed database: Data is distributed across different sites
  • Cloud database: Created and maintained using cloud data services that provide defined performance measures for the database

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©2015 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

Types of Databases

  • General-purpose databases: Contains a wide variety of data used in multiple disciplines
  • Discipline-specific databases: Contains data focused on specific subject areas

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©2015 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

Types of Databases

  • Operational database: Designed to support a company’s day-to-day operations
  • Analytical database: Stores historical data and business metrics used exclusively for tactical or strategic decision making
  • Data warehouse: Stores data in a format optimized for decision support

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©2015 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

Types of Databases

  • Online analytical processing (OLAP)
  • Enable retrieving, processing, and modeling data from the data warehouse
  • Business intelligence: Captures and processes business data to generate information that support decision making

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©2015 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

Types of Databases

  • Unstructured data: It exists in their original state
  • Structured data: It results from formatting
  • Structure is applied based on type of processing to be performed
  • Semistructured data: Processed to some extent
  • Extensible Markup Language (XML)
  • Represents data elements in textual format

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©2015 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

Database Design

  • Focuses on the design of the database structure that will be used to store and manage end-user data
  • Well-designed database
  • Facilitates data management
  • Generates accurate and valuable information
  • Poorly designed database causes difficult-to-trace errors

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©2015 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

Evolution of File System Data Processing

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Table 1.2 - Basic File Terminology

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Figure1.6 - A Simple File System

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Problems with File System Data Processing

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Structural and Data Dependence

  • Structural dependence: Access to a file is dependent on its own structure
  • All file system programs are modified to conform to a new file structure
  • Structural independence: File structure is changed without affecting the application’s ability to access the data

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©2015 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

Structural and Data Dependence

  • Data dependence
  • Data access changes when data storage characteristics change
  • Data independence
  • Data storage characteristics is changed without affecting the program’s ability to access the data
  • Practical significance of data dependence is difference between logical and physical format

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©2015 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

Data Redundancy

  • Unnecessarily storing same data at different places
  • Islands of information: Scattered data locations
  • Increases the probability of having different versions of the same data

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Data Redundancy Implications

  • Poor data security
  • Data inconsistency
  • Increased likelihood of data-entry errors when complex entries are made in different files
  • Data anomaly: Develops when not all of the required changes in the redundant data are made successfully

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Types of Data Anomaly

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Lack of Design and Data-Modeling Skills

  • Evident despite the availability of multiple personal productivity tools being available
  • Data-modeling skills is vital in the data design process
  • Good data modeling facilitates communication between the designer, user, and the developer

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©2015 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

Database Systems

  • Logically related data stored in a single logical data repository
  • Physically distributed among multiple storage facilities

DBMS eliminates most of file system’s problems

  • Current generation DBMS software:

Stores data structures, relationships between structures, and access paths

Defines, stores, and manages all access paths and components

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©2015 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

Figure 1.8 - Contrasting Database and �File Systems

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Figure 1.9 - The Database System Environment

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©2015 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

DBMS Functions

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Data dictionary management

Data storage management

Data transformation and presentation

Security management

  • Data dictionary: Stores definitions of the data elements and their relationships
  • Performance tuning: Ensures efficient performance of the database in terms of storage and access speed
  • Transforms entered data to conform to required data structures
  • Enforces user security and data privacy

©2015 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

DBMS Functions

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Multiuser access control

Backup and recovery management

Data integrity management

  • Sophisticated algorithms ensure that multiple users can access the database concurrently without compromising its integrity
  • Enables recovery of the database after a failure
  • Minimizes redundancy and maximizes consistency

©2015 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

DBMS Functions

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Database access languages and application programming interfaces

Database communication interfaces

  • Query language: Lets the user specify what must be done without having to specify how
  • Structured Query Language (SQL): De facto query language and data access standard supported by the majority of DBMS vendors
  • Accept end-user requests via multiple, different network environments

©2015 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

Disadvantages of Database Systems

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Table 1.3 - Database Career Opportunities

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