1. IS605/606: Information Systems Instructor: Dr. Boris Jukic
Relational Database Systems in Enterprise Information Systems

2. 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 is changed (such as deletion or addition of a field), the related file management programs have to be modified accordingly
Data dependence refers to the fact that the changes in data characteristics, 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

3. Data Redundancy
When the same data is stored in more than one 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 to update all multiple copies of the same data
Data anomalies: modification, insertion and deletion

4. Data Redundancy in File Systems and Resulting Anomalies
Modification anomaly: if PlainSounder model description changes
Insertion Anomaly: if a new customer (Toyota for example) is added to the list of those who buy BetterBox product

5. Database Systems
Database Systems achieve data independence and structural 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 physically separated and unrelated files

6. 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

7. 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. Relational Database Management System
In RMDBS, all data appears to be stored in a collection of tables (or relations), which are independent of one another, but can be linked through common entries in one of the tables' columns or fields (controlled redundancy)
Relational Schema: The graph depicting relationship types between tables

9. Relational Schema

10. 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
Customer ID
Customer Name
Customer Location
Product ID C1
Chrysler
Germany
001 C2
Circuit City
California H1
Hyundai
Korea G1 GM
Michigan
002 F1
Ford Motors H2
Honda
Japan
003 B1
BMW
Customers

11. 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) from the 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 uniquely identifying each row (entity), satisfying the entity integrity conditions. Null value (no entry) is not permitted for a primary key.
The order of rows and columns within the table is irrelevant
Foreign Key is an attribute in one table whose values must either 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.

12. 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 relationships through a so called composite (bridge) entity

13. Enterprise data planning
A large component of the business informational needs can be captured by the mapping of all entities the organizations need to keep track of and the relationships among them
E-R (Entity-Relationship) modeling is a standard technique that provides a simplified picture of the relationship among entities.

14. Keys and Relationships: transaction processing system example

15. 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

16. 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
Logical view – focuses on how users logically access information to meet particular business needs

17. Increased Scalability and Performance
A database must scale to meet increased demand, while maintaining acceptable performance levels
Scalability – refers to how well a system can adapt to increased demands
Performance – measures how quickly a system performs a certain process or transaction

18. Reduced Information Redundancy
Databases reduce information redundancy
Redundancy – the duplication of information or storing the same information in multiple places
Inconsistency is one of the primary problems with redundant information

19. Increase Information Integrity (Quality)
Information integrity – a measure of the quality of information
Integrity constraints – rules that help ensure the quality of information
Operational integrity constraints – rules that enforce basic and fundamental information-based constraints
Business-critical integrity constraints – rules that enforce business rules vital to an organization’s success and often require more insight and knowledge than operational integrity constraints

20. Increased Information Security
Information is an organizational asset and must be protected
Databases offer several security features including:
Passwords – provide authentication of the user
Access levels – determine who has access to the different types of information
Access controls – Determine types of user access, such as read-only access

21. DATABASE MANAGEMENT SYSTEMS
Database management systems (DBMS) – software through which users and application programs interact with a database

22. INTEGRATING INFORMATION AMONG MULTIPLE DATABASES
Organizations typically maintain multiple systems, each with its own database
Integration – allows separate systems to communicate directly with each other

23. INTEGRATING INFORMATION AMONG MULTIPLE DATABASES
Forward integration – takes information entered into a given system and sends it automatically to all downstream systems and processes

24. INTEGRATING INFORMATION AMONG MULTIPLE DATABASES
Backward integration – takes information entered into a given system and sends it automatically to all upstream systems and processes

25. INTEGRATING INFORMATION AMONG MULTIPLE DATABASES
Building a central repository specifically for integrated information