Database Fundamentals- Content Analysis
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Week1-Lectureslides-202006171.zipChap1 .pptx
Database Principles: Fundamentals of Design, Implementations and Management
CHAPTER 1
THE DATABASE APPROACH
In this chapter, you will learn:
The difference between data and information
What a database is, what the different types of databases are, and why they are valuable assets for decision making
The importance of database design
How modern databases evolved from file systems
About flaws in file system data management
What the database system’s main components are and how a database system differs from a file system
The main functions of a database management system (DBMS)
The role of Open Source Database Systems
The importance of Data Governance and Data Quality
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Data vs. Information
Data:
Raw facts; building blocks of information
Unprocessed information
Information:
Data processed to reveal meaning
Accurate, relevant, and timely information is the key to good decision making
Good decision making is the key to survival in a global environment
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Transforming Raw Data into Information Fig 1.1 p6 Initial survey screen
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Transforming Raw Data into Information (cont..) Fig 1.1 Information in graphic format
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Data Quality and Data Governance
Data Quality can be examined at a number of different levels including:
Accuracy: Is the data accurate and come from a verifiable source?
Relevance: Is the data relevant to the organisation?
Completeness: Is the required data being stored?
Timeliness: Is the data updated frequently in order to meet the business requirements?
Uniqueness: Is the data unique and there is no redundancy in the database?
Unambiguous: Is the meaning of the data clear.
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Data Quality and Data Governance (cont…)
Data governance is the term used to describe a strategy or methodology defined by an organisation to safeguard data quality.
Each organisation produces its own data governance strategy which will involve the development of a series of policies and procedures for managing availability, usability, quality, integrity, and security of data within the organisation.
Introducing the Database and the DBMS
Database—shared, integrated computer structure that stores:
End user data (raw facts)
Metadata (data about data)
DBMS (database management system):
Collection of programs that manages database structure and controls access to data
Possible to share data among multiple applications or users
Makes data management more efficient and effective
The DBMS hides much of the database’s internal complexity from the application programs and users.
The application program might be written by a programmer using a programming language such as COBOL, Visual basic, C++, or Java or it might be created through a DBMS utility program.
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Role and Advantages of the DBMS (cont.)
A DBMS provides advantages such as :
Improved data sharing. Users have better access to more and better-managed data
Better data integration. Promotes integrated view of organization’s operations
Minimised data inconsistency. Probability of data inconsistency is greatly reduced
Improved data access. Possible to produce quick answers to ad hoc queries
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Role and Advantages of the DBMS (cont..)
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Types of Databases
Single-user:
Supports only one user at a time
Desktop:
Single-user database running on a personal computer
Multi-user:
Supports multiple users at the same time
Workgroup:
Multi-user database that supports a small group of users or a single department
Enterprise:
Multi-user database that supports a large group of users or an entire organization
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Types of Databases (cont..)
Can be classified by location:
Centralized:
Supports data located at a single site
Distributed:
Supports data distributed across several sites
Can be classified by use:
Transactional (or production):
Supports a company’s day-to-day operations
Data warehouse:
Stores data used to generate information required to make tactical or strategic decisions
Often used to store historical data
Structure is quite different
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Why Database Design is Important
Database design refers to the activities that focus on the design of the database structure that will be used to store and manages end-user data.
Defines the database’s expected use
Different approach needed for different types of databases
Avoid redundant data
Poorly designed database generates errors leads to bad decisions can lead to failure of organization
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Historical Roots: Files and Data Processing
Managing data with file systems is obsolete
Understanding file system characteristics makes database design easier to understand
Awareness of problems with file systems helps prevent similar problems in DBMS
Knowledge of file systems is helpful if you plan to convert an obsolete file system to a DBMS
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Historical Roots: Files and Data Processing (cont..)
Manual File systems:
Collection of file folders kept in file cabinet
Organization within folders based on data’s expected use (ideally logically related)
System adequate for small amounts of data with few reporting requirements
Finding and using data in growing collections of file folders became time-consuming and cumbersome
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Historical Roots: Files and Data Processing (cont..)
Computerised file systems:
Conversion from manual to computer system:
Could be technically complex, requiring hiring of data processing (DP) specialists
Resulted in numerous “home-grown” systems being created
Initially, computer files were similar in design to manual files (see Figure 1.3)
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Historical Roots: Files and Data Processing cont..)
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Historical Roots: Files and Data Processing (cont..)
Fig 1.3
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Historical Roots: Files and Data Processing (cont..)
DP specialist wrote programs for reports:
Monthly summaries of types and amounts of insurance sold by agents
Monthly reports about which customers should be contacted for renewal
Reports that analyzed ratios of insurance types sold by agent
Customer contact letters summarizing coverage
Other departments requested databases be written for them
SALES database created for sales department
AGENT database created for personnel department (see Fig 1.4 next)
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Historical Roots: Files and Data Processing (cont…)
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Historical Roots: Files and Data Processing(cont..)
As number of databases increased, small file system evolved
Each file used its own application programs
Each file was owned by individual or department who commissioned its creation
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Historical Roots: Files and Data Processing (cont)
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Example of Early Database Design (cont…)
As system grew, demand for DP’s (Data Specialists) programming skills grew
Additional programmers hired
DP specialist evolved into DP manager, supervising a DP department
Primary activity of department (and DP manager) remained programming
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Problems with File System Data Management
Every task requires extensive programming in a third-generation language (3GL)
Programmer must specify task and how it must be done
Modern databases use fourth-generation languages (4GL)
Allow users to specify what must be done without specifying how it is to be done
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Problems with File System Data Management
Lengthy development times.
Difficulty in getting quick answers.
Complex System Administration
Lack of security and limited data sharing
Extensive Programming
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Structural and Data Dependence
Structural dependence (SD)
A file systems exhibits SD; that is, access to a file depends on its structure
Data independence
Changes in the data storage characteristics without affecting the application program’s ability to access the data
The practical significance of data dependence is the difference between the:
Logical data format
How the human being views the data
And the Physical data format
How the computer “sees” the data
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Field Definitions and Naming Conventions
Flexible record definition anticipates reporting requirements by breaking up fields into their component parts
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Data Redundancy
Data redundancy results in data inconsistency
Different and conflicting versions of the same data appear in different places
Errors more likely to occur when complex entries are made in several different files and/or recur frequently in one or more files
A Data anomaly develops when required changes in the redundant data are not made successfully
Types of data anomalies:
Update anomalies
Occur when changes must be made to existing records
Insertion anomalies
Occur when entering new records
Deletion anomalies
Occur when deleting records
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Database Systems
Problems inherent in file systems make using a database system very desirable
File system
Many separate and unrelated files
Database
Logically related data stored in a single logical data repository
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Database Systems
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The Database System Environment
Database system is composed of five main parts:
Hardware
Software
Operating system software
DBMS software
Application programs and utility software
People
Procedures
Data
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The Database System Environment (cont…)
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DBMS Functions
DBMS performs functions that guarantee integrity and consistency of data
Data dictionary management
defines data elements and their relationships
Data storage management
stores data and related data entry forms, report definitions, etc.
Data transformation and presentation
translates logical requests into commands to physically locate and retrieve the requested data
Security management
enforces user security and data privacy within database
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DBMS Functions (cont…)
Multiuser access control
uses sophisticated algorithms to ensure multiple users can access the database concurrently without compromising the integrity of the database
Backup and recovery management
provides backup and data recovery procedures
Data integrity management
promotes and enforces integrity rules
Database access languages and application programming interfaces
provide data access through a query language
Database communication interfaces
allow database to accept end-user requests via multiple, different network environments
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DBMS Functions (continued)
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DBMS Functions (cont…)
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Summary
Data are raw facts. Information is the result of processing data to reveal its meaning.
To implement and manage a database, use a DBMS.
Database design defines the database structure.
A well-designed database facilitates data management and generates accurate and valuable information.
A poorly designed database can lead to bad decision making, and bad decision making can lead to the failure of an organization.
Databases were preceded by file systems.
Limitations of file system data management:
requires extensive programming
system administration complex and difficult
making changes to existing structures is difficult
security features are likely to be inadequate
independent files tend to contain redundant data
DBMS’s were developed to address file systems’ inherent weaknesses
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Types of Databases (cont..)
Open Source
Open Source software is that it is free to acquire and use the product itself.
However, there will be costs involved in the development and on-going support of the software.
LAMP is used to define the most the most popular open source software namely; Linux, Apache Web server, MySQL DBMS, and the Perl PHP/Python development languages.
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