Lecture 04 data resource management
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Transcript of Lecture 04 data resource management
DATA RESOURCE
MANAGEMENTPresented by:
Dr. Akhlas AhmedLecture # 04
Preston University
File Organization:Terms & Concept
Binary: means composed of two pieces or two parts and may refer to:
Mathematics:Binary number, a representation for numbers using only two digits
(0 and 1)Binary relation, a mathematical relation involving two elementsBinary function, a function in mathematics that takes two
argumentsComputingBinary file, composed of something other than human-readable textExecutable, a type of binary file that contains machine code for the
computer to executeBinary code, the digital representation of text and data
File Organization:Terms & Concept
Multiples of bits
Decimal
Value Metric
1000 kbit kilobit
10002 Mbit megabit
10003 Gbit gigabit
10004 Tbit terabit
10005 Pbit petabit
10006 Ebit exabit
10007 Zbit zettabit
10008 Ybit yottabit
Binary
Value JEDEC IEC
1024 Kbit kilobit Kibit kibibit
10242 Mbit megabit Mibit mebibit
10243 Gbit gigabit Gibit gibibit
10244 - - Tibit tebibit
10245 - - Pibit pebibit
10246 - - Eibit exbibit
10247 - - Zibit zebibit
10248 - - Yibit yobibitSee also: Nibble · Byte · Bit and Byte prefixes
Orders of magnitude of data
File Organization:Terms & Concept
• Bit: A bit is the basic unit of information in computing and digital communications. A bit can have only one of two values, and may therefore be physically implemented with a two-state device. The most common representation of these values are 0and1. The term bit is a contraction of binary digit.
Smallest unit of data; binary digit (0,1) Byte: Group of bits that represents a single
character Field: Group of words or a complete number
File Organization:Terms & Concept
Record: Group of related fields
File: Group of records of same type
Database: Group of related files
Data Hierarchy:in a Computer System
Figure 7-1
File Organization:Terms & Concept
Entity: Person, place, thing, event about which information is maintained
Attribute: Description of a particular entity
Key field: Identifier field used to retrieve, update, sort a record
ORGANIZING DATA: IN A TRADITIONAL FILE
ENVIRONMENT
Figure 7-2
Problems with the Traditional File Environment
Data redundancy Data redundancy occurs in database systems which have a field that is repeated in two or more tables.
o Program-Data dependence A Flow dependency, also known as a data dependency or true dependency or read-after-write (RAW), occurs when an instruction depends on the result of a previous instruction:1. A = 3 2. B = A 3. C = B
Lack of flexibility Poor security Lack of data-sharing and availability
Traditional File Processing
Figure 7-3
Database Management System (DBMS)
• Creates and maintains databasesCreates and maintains databases
• Eliminates requirement for data definition Eliminates requirement for data definition statementsstatements
• Acts as interface between application Acts as interface between application programs and physical data filesprograms and physical data files
• Separates logical and physical views of Separates logical and physical views of datadata
The Contemporary Database Environment
Figure 7-4
Components of DBMS
• Data definition language: Data definition language: Specifies Specifies content and structure of database and content and structure of database and defines each data elementdefines each data element
• Data manipulation language:Data manipulation language:Manipulates data in a databaseManipulates data in a database
• Data dictionary:Data dictionary: Stores definitions of Stores definitions of data elements, and data characteristicsdata elements, and data characteristics
Sample Data Dictionary Report
Figure 7-5
Types of Databases
• Relational DBMSRelational DBMS
• Hierarchical and Network DBMSHierarchical and Network DBMS
• Object-Oriented DatabasesObject-Oriented Databases
Relational DBMS
• Represents data as two-dimensional tables Represents data as two-dimensional tables called relationscalled relations
• Relates data across tables based on common Relates data across tables based on common data elementdata element
• Examples: DB2, Oracle, MS SQL ServerExamples: DB2, Oracle, MS SQL Server
Relational Data Model
Figure 7-6
Three Basic Operations in a Relational Database
• Select:Select: Creates subset of rows that meet Creates subset of rows that meet specific criteriaspecific criteria
• Join:Join: Combines relational tables to provide Combines relational tables to provide users with informationusers with information
• Project:Project: Enables users to create new tables Enables users to create new tables containing only relevant informationcontaining only relevant information
Three Basic Operations in a Relational Database
Figure 7-7
Hierarchical and Network DBMS
Hierarchical DBMSHierarchical DBMS
• Organizes data in a tree-like structureOrganizes data in a tree-like structure
• Supports one-to-many parent-child Supports one-to-many parent-child relationshipsrelationships
• Prevalent in large legacy systemsPrevalent in large legacy systems
Hierarchical DBMS
Figure 7-8
Hierarchical and Network DBMS
Network DBMSNetwork DBMS
• Depicts data logically as many-to-many Depicts data logically as many-to-many relationshipsrelationships
Network DBMS
Figure 7-9
Hierarchical and Network DBMS
Disadvantages
Outdated
Less flexible compared to RDBMS
Lack support for ad-hoc and English language-like queries
Object-Oriented Databases
Object-oriented DBMS: Stores data and procedures as objects that can be retrieved and shared automatically
Object-relational DBMS: Provides capabilities of both object-oriented and relational DBMS
Querying Databases: Elements of SQL
Basic SQL Commands
SELECT: Specifies columns
FROM: Identifies tables or views
WHERE: Specifies conditions
Results of SELECT Statement
Results of Conditional Selection
137150
Door latchDoor seal
22.506.00
Projection from Joining PART and SUPPLIER Tables
Designing Databases
Conceptual design: Abstract model of database from a business perspective
Physical design: Detailed description of business information needs
Designing Databases
Entity-relationship diagram: Methodology for documenting databases illustrating relationships between database entities
Normalization: Process of creating small stable data structures from complex groups of data
CREATING A DATABASE ENVIRONMENT
CREATING A DATABASE ENVIRONMENT
CREATING A DATABASE ENVIRONMENT
Figure 7-15
An Normalized Relation of ORDER
Distributing Databases
Centralized database
Used by single central processor or multiple processors in client/server network
Distributing Databases
Distributed database
Stored in more than one physical location
Partitioned database
Duplicated database
Distributing Databases
Figure 7-16
Management Requirements for Database Systems
Key elements in a database environment:
Data Administration
Data Planning and Modeling Methodology
Database Technology and Management
Users
Management Requirements for Database Systems
Figure 7-17
Multidimensional Data Analysis
On-line analytical processing (OLAP)
Multidimensional data analysis
Supports manipulation and analysis of large volumes of data from multiple dimensions/perspectives
Multidimensional Data Model
Figure 7-18
Data Warehousing and Datamining
Data warehouse
Supports reporting and query tools
Stores current and historical data
Consolidates data for management analysis and decision making
Components of Data Warehouse
Figure 7-19
Data Warehouse and data mining
Data mart
Subset of data warehouse
Contains summarized or highly focused portion of data for a specified function or group of users
Data Warehouse and data mining
Datamining
Tools for analyzing large pools of data
Find hidden patterns and infer rules to predict trends
Benefits of Data Warehouse
Improved and easy accessibility to information
Ability to model and remodel the data
Database and the web
Hypermedia databaseHypermedia database
• Organizes data as network of nodesOrganizes data as network of nodes
• Links nodes in pattern specified by userLinks nodes in pattern specified by user
• Supports text, graphic, sound, video and Supports text, graphic, sound, video and executable programsexecutable programs
Database Trends
Figure 7-20
A Hypermedia Database
Database Trends
Database server
Computer in a client/server environment runs a DBMS to process SQL statements and perform database management tasks
Application server
Software handling all application operations
Databases and the Web
Database Trends
Figure 7-21
Linking Internal Databases to the Web
Thank You