Relational Databases in Enterprise Information Systems
-
Upload
sharath-kumar-ps -
Category
Documents
-
view
221 -
download
0
Transcript of Relational Databases in Enterprise Information Systems
8/7/2019 Relational Databases in Enterprise Information Systems
http://slidepdf.com/reader/full/relational-databases-in-enterprise-information-systems 1/25
IS605/606: Information Systems
Instructor: Dr. Boris Jukic
Relational Database Systems in
Enterprise Information Systems
8/7/2019 Relational Databases in Enterprise Information Systems
http://slidepdf.com/reader/full/relational-databases-in-enterprise-information-systems 2/25
File systems
File systems rely on coded file management programs to access,insert and modify their content
As such, file systems are plagued by two main problems
Structural dependence refers to the fact that if a file structure ischanged (such as deletion or addition of a field), the related filemanagement programs have to be modified accordingly
Data dependence refers to the fact that the changes in datacharacteristics, such as changing a field from integer to decimal(or even just changing the length of the field), will cause the
related file management programs to be changed Finally, there is a problem of data redundancy
8/7/2019 Relational Databases in Enterprise Information Systems
http://slidepdf.com/reader/full/relational-databases-in-enterprise-information-systems 3/25
Data Redundancy
When the same data is stored in more thanone location (in multiple files or multiple fields
within one file) It may lead to: Data integrity (inconsistency) problems
may be caused by either data entry errors or failure toupdate all multiple copies of the same data
Data anomalies: modification, insertion anddeletion
8/7/2019 Relational Databases in Enterprise Information Systems
http://slidepdf.com/reader/full/relational-databases-in-enterprise-information-systems 4/25
8/7/2019 Relational Databases in Enterprise Information Systems
http://slidepdf.com/reader/full/relational-databases-in-enterprise-information-systems 5/25
Database Systems
Database Systems achieve data independence andstructural independence If data type of as filed is changed or a field is eliminated or
a new one added, the existing management programs(queries) do NOT have to be modified
If properly designed, databases have a low level of redundancy, eliminating most of the insertion,deletion and modification anomalies
Logically related data instead of physicallyseparated and unrelated files
8/7/2019 Relational Databases in Enterprise Information Systems
http://slidepdf.com/reader/full/relational-databases-in-enterprise-information-systems 6/25
Four (Logical) Data Models
Hierarchical Model (Legacy)
Standard tree-like structure
Network Model (Legacy)
More than one parent allowed Relational Model
First truly data and structurally independent model
No predetermined navigational maps as in two older
models
The Database technology of choice
Object Model
Tables become objects
8/7/2019 Relational Databases in Enterprise Information Systems
http://slidepdf.com/reader/full/relational-databases-in-enterprise-information-systems 7/25
RELATIONAL DATABASE
ADVANTAGES Database advantages from a business
perspective include
Increased flexibility
Increased scalability and performance
Reduced information redundancy
Increased information integrity (quality)
Increased information security
8/7/2019 Relational Databases in Enterprise Information Systems
http://slidepdf.com/reader/full/relational-databases-in-enterprise-information-systems 8/25
Relational Database Management System
In RMDBS, all data appears to be stored in acollection of tables (or relations), which are
independent of one another, but can belinked through common entries in one of thetables' columns or fields (controlledredundancy)
Relational Schema: The graph depictingrelationship types between tables
8/7/2019 Relational Databases in Enterprise Information Systems
http://slidepdf.com/reader/full/relational-databases-in-enterprise-information-systems 9/25
Relational Schema
8/7/2019 Relational Databases in Enterprise Information Systems
http://slidepdf.com/reader/full/relational-databases-in-enterprise-information-systems 10/25
Reduced Data Redundancy
Products Product Id Product Name Product Description Product Price
001 PlainSounder AM FM Radio, 2 speakers $51.00
002 BetterBox Radio, CD, 6 Speakers $123.00
003 UltraX CD, MP3, 8 Speakers $270.00
Customers
Customer
ID
Customer
Name
Customer
Location
Product
ID
C1 Chrysler Germany 001
C2 Circuit City California 001
H1 Hyundai Korea 001
G1 GM Michigan 002
F1 Ford Motors Michigan 002
H2 Honda Japan 003
B1 BMW Germany 003
8/7/2019 Relational Databases in Enterprise Information Systems
http://slidepdf.com/reader/full/relational-databases-in-enterprise-information-systems 11/25
Tables in RDBMS
Tables: Logical constructs containing individual entity sets. Tables are always two-dimensional: rows and columns
each row represents a single entity (or entity instance) fromthe entity set
each (uniquely named) column represents one attribute each row-column intersection results in a single data value
Each table must have a primary key : An attribute uniquelyidentifying each row (entity), satisfying the entity integrity
conditions. Null value (no entry) is not permitted for aprimary key.
The order of rows and columns within the table is irrelevant
Foreign Key is an attribute in one table whose values musteither match the value of a primary key in another table or be set to null (no value). These conditions are known as
referential integrity constraint.
8/7/2019 Relational Databases in Enterprise Information Systems
http://slidepdf.com/reader/full/relational-databases-in-enterprise-information-systems 12/25
Relationships within the relational
database:� One-to-one relationships:
� One-to many relationships:� Examples:
� professor - class� department - employee
� Many to-many relationships� Examples: parts ± product, student ± class, «
� it is recommended to break it into a set(usually two) of one-to-may relationshipsthrough a so called composite (bridge) entity
8/7/2019 Relational Databases in Enterprise Information Systems
http://slidepdf.com/reader/full/relational-databases-in-enterprise-information-systems 13/25
Enterprise data planning
� A large component of the business
informational needs can be captured bythe mapping of all entities theorganizations need to keep track of andthe relationships among them
� E-R (Entity-Relationship) modeling is astandard technique that provides a simplifiedpicture of the relationship among entities.
8/7/2019 Relational Databases in Enterprise Information Systems
http://slidepdf.com/reader/full/relational-databases-in-enterprise-information-systems 14/25
K eys and Relationships: transaction
processing system example
8/7/2019 Relational Databases in Enterprise Information Systems
http://slidepdf.com/reader/full/relational-databases-in-enterprise-information-systems 15/25
RELATIONAL DATABASE
ADVANTAGES Database advantages from a business
perspective include
Increased flexibility
Increased scalability and performance
Reduced information redundancy
Increased information integrity (quality)
Increased information security
8/7/2019 Relational Databases in Enterprise Information Systems
http://slidepdf.com/reader/full/relational-databases-in-enterprise-information-systems 16/25
Increased Flexibility
A well-designed database should:
Handle changes quickly and easily
Provide users with different views
A database has only one physical view
Physical view ± deals with the physical storage of information on a storage device such as a hard disk
A database can have multiple logical views
Log ical view ± focuses on how users logically accessinformation to meet particular business needs
8/7/2019 Relational Databases in Enterprise Information Systems
http://slidepdf.com/reader/full/relational-databases-in-enterprise-information-systems 17/25
Increased Scalability and Performance
A database must scale to meet increaseddemand, while maintaining acceptableperformance levels
S calability ± refers to how well a system canadapt to increased demands
Perf ormance ± measures how quickly a systemperforms a certain process or transaction
8/7/2019 Relational Databases in Enterprise Information Systems
http://slidepdf.com/reader/full/relational-databases-in-enterprise-information-systems 18/25
Reduced Information Redundancy
Databases reduce information redundancy
R edundancy ± the duplication of information or storing the same information in multiple places
Inconsistency is one of the primary problemswith redundant information
8/7/2019 Relational Databases in Enterprise Information Systems
http://slidepdf.com/reader/full/relational-databases-in-enterprise-information-systems 19/25
Increase Information Integrity
(Quality) I nf ormati on integ rity ± a measure of the quality of information
I nteg rity c onstraints ± rules that help ensure the quality of information
Operati onal integ rity c onstraints ± rules that enforcebasic and fundamental information-based constraints
Business-critical integ rity c onstraints ± rules thatenforce business rules vital to an organization¶s successand often require more insight and knowledge than
operational integrity constraints
8/7/2019 Relational Databases in Enterprise Information Systems
http://slidepdf.com/reader/full/relational-databases-in-enterprise-information-systems 20/25
Increased Information Security
Information is an organizational asset andmust be protected
Databases offer several security featuresincluding:
Passwords ± provide authentication of the user
Access levels ± determine who has access to thedifferent types of information
Access controls ± Determine types of user access, such as read-only access
8/7/2019 Relational Databases in Enterprise Information Systems
http://slidepdf.com/reader/full/relational-databases-in-enterprise-information-systems 21/25
DATABASE MANAGEMENT
SYSTEMS Database manag ement systems ( DBM S) ±
software through which users and applicationprograms interact with a database
8/7/2019 Relational Databases in Enterprise Information Systems
http://slidepdf.com/reader/full/relational-databases-in-enterprise-information-systems 22/25
INTEGRATING INFORMATION
AMONG MULTIPLE DATABASES Organizations typically maintain multiple
systems, each with its own database
I nteg rati on ± allows separate systems tocommunicate directly with each other
8/7/2019 Relational Databases in Enterprise Information Systems
http://slidepdf.com/reader/full/relational-databases-in-enterprise-information-systems 23/25
INTEGRATING INFORMATION
AMONG MULTIPLE DATABASES F orward integ rati on ± takes information entered into a given systemand sends it automatically to all downstream systems and processes
8/7/2019 Relational Databases in Enterprise Information Systems
http://slidepdf.com/reader/full/relational-databases-in-enterprise-information-systems 24/25
INTEGRATING INFORMATION
AMONG MULTIPLE DATABASES Backward integ rati on ± takes information entered into a given systemand sends it automatically to all upstream systems and processes
8/7/2019 Relational Databases in Enterprise Information Systems
http://slidepdf.com/reader/full/relational-databases-in-enterprise-information-systems 25/25
INTEGRATING INFORMATION
AMONG MULTIPLE DATABASES
Building acentral
repositoryspecificallyfor integratedinformation