Web-Enabled Decision Support Systems

1. Web-Enabled Decision Support Systems Introduction to Databases Prof. Name name@email.com Position (123) 456-7890 University Name

2. Overview • 2.1 Introduction • 2.2 Data, Information, and Metadata • 2.3 File-Based Approach • 2.4 Database Approach • 2.5 Database Development Process • 2.6 Data Models • 2.7 Summary

3. Introduction • The desire to collect, organize, and easily access information predates computer technology • Oral records • Written records (books) • Computers, like books, have altered the way we collect, store, and retrieve information • A database is a computer solution for fast, efficient, accurate, and secure data access • Play a crucial role in the growing dominance of internet-based technology • Used for a variety of purposes: • Online shopping • Driving directions • Class enrollment and online grades

4. Overview • 2.1 Introduction • 2.2 Data, Information, and Metadata • 2.3 File-Based Approach • 2.4 Database Approach • 2.5 Database Development Process • 2.6 Data Models • 2.7 Summary

5. Data • The term datarefers to known facts that can be recorded and preserved • Include text, graphics, images, and/or video Data in Context

6. Information • Informationis the processed data presented in a form suitable for human interpretation • The same data can be processed in a variety of ways to generate different kinds of information Information – Pie Chart

7. Metadata • Metadata is data about data • Process of information building demands an additional description of data to be processed Metadata

8. Overview • 2.1 Introduction • 2.2 Data, Information, and Metadata • 2.3 File-Based Approach • 2.4 Database Approach • 2.5 Database Development Process • 2.6 Data Models • 2.7 Summary

9. Evolution of Database Systems • Two approaches to convert data to information: • File-based • Developed in 1980’s • Stores, manipulates, retrieves data from large flat files • Database (relational systems) • Developed by E. F. Codd of IBM in the early 1980's • Widely used today Evolution of Database Systems

10. File-Based Approach • A file is a collection of related information • A system of files and collection of application programs manipulating them is a file-based system The University’s File-Based System

11. Limitations of File-Based Approach • Efforts for query answering: • What is the average grade for Dr. John Doe’s students? • List the activities for all students enrolled in EZZ 4162. • Which personnel are students as well as staff? • Other limitations: • Duplication of data • Data dependency • Slow development, high maintenance and fixed queries

12. Overview • 2.1 Introduction • 2.2 Data, Information, and Metadata • 2.3 File-Based Approach • 2.4 Database Approach • 2.5 Database Development Process • 2.6 Data Models • 2.7 Summary

13. The Database System • Limitations of file-based approach tell us that: • Parameters defining data should be separately stored • There should be a way to control and manipulate data in isolation of the application program • A database management system(DBMS) is a piece of software that allows a user to define, create, and manage access to a database • Decouples application programs from data • The database stores all its data in one location, thereby limiting data duplication • A database system can be defined as the combination of a database, a DBMS, and application programs • Because of the advantages offered by a DBMS, businesses and organizations prefer the database approach to the file-based approach

14. University’s Database System

15. Components of a Database System • There are four components in any database system: • Users • Database application • DBMS • Database Components of a Database System

16. Components of a Database System (cont.) • Database: • A collection of logically related data • Database management system (DBMS): • Software that allows users to define, create, and manage database access • Popular database management systems: • Access, Oracle, IBM’s DB2, and SQL Server • Database applications: • Computer programs that allow users to manipulate the data in a DBMS through a user-friendly interface • Can be divided into four broad categories: • Personal: Restricted to a single user • Departmental: Referenced by hundreds of users over a shared system or network • Enterprise: Extensions of departmental applications involving thousands of users • Internet: Largest form of information sharing wherein billions of users are involved

17. Components of a Database System (cont.) • Database administrator, system developer, and end user: • A database administrator (DBA) is a person responsible for all the data resources of an organization • Uses tools that come with a DBMS to improve the productivity and performance of database planning and design • System developers are a group of people responsible for the creation of new application programs that cater to the user requirements • Use their own tools to write programs that communicate with the DBMS • End-users in an organization can add, update, and delete data in a database through application programs or directly through a DBMS • Use the application program to accomplish their day-to-day tasks

18. Functions of a DBMS • A DBMS is primarily responsible for providing a logical view of underlying data • Allows its user to store, retrieve, and update data in the database • Provides a clear and logical view of the process that manipulates the data • Other functionalities: • Data independence • Maintain segregation between the program and the data • Concurrency control • Recovery services • Utility services • Perform initialization and maintenance operations on a database

19. Advantages and Disadvantages of Database Approach • Advantages: • Segregation of the application program and the data • Minimal data duplication • Ability to retrieve data easily • Reduced development time and maintenance needs • Disadvantages: • Complexity • Size • Cost

20. Overview • 2.1 Introduction • 2.2 Data, Information, and Metadata • 2.3 File-Based Approach • 2.4 Database Approach • 2.5 Database Development Process • 2.6 Data Models • 2.7 Summary

21. Database Development Process • Enterprise modeling: • Describes the data needed for database system • Conceptual database modeling: • Entity-relationship (E-R) modeling • Logical database design: • Relational data modeling is used to transform the E-R diagram into a relational schema • Physical database design and creation: • Selection of software (DBMS) and hardware

22. Schema • The process of database development can also be explained using schema, an overall description of the database • Three types of schemas, defined by their levels of abstraction: • External schema: • Describes the database in terms of data viewed by different users • Conceptual schema: • Describes the database in terms of entities, attributes, and relationships, along with its integrity constraints • Internal schema: • Describes the database in terms of stored records, data fields, and indexes

23. Three-Tier Architecture

24. Database Development Process

25. Overview • 2.1 Introduction • 2.2 Data, Information, and Metadata • 2.3 File-Based Approach • 2.4 Database Approach • 2.5 Database Development Process • 2.6 Data Models • 2.7 Summary

26. Data Models • Adata model is a collection of concepts for describing data, its relationships, and its constraints • Provides a clearer and more accurate description and representation of data • Standard platform that enables database designers and end-users to communicate • Come in three varieties: • Object-based models (conceptual schema) • Record-based models (external schema) • Physical data models (internal schema)

27. Object-Based Data Models • Object-based data models use entities, attributes, and relationships to present information • An entity is a living or non-living object in the real world • Examples: Person, place, event • An attribute is a property of an entity • Examples: Name, address of a person • A relationship is an association between entities • Example: Register is a relationship between student and courses • Some common types of object-based data models include: • Entity-relationship data model • Functional data model • Object-oriented data model

28. Entity-Relationship Data Model • The entity-relationship model has emerged as one of the most popular and widely used techniques in today's databases • Describes data in the form of an E-R diagram: • Entities are rectangles (“Student” and “Department”) • Relationships are diamonds (“Belongs to”) • Attributes are ovals (“SSN”, “Name”) • Cardinalities are constraints on relationships (“>” and “|”) Entity-Relationship Diagram

29. Record-Based Data Models • Record-based data models use recordsto present data • A record is a structure that contains a fixed number of fields to hold a piece of information • There are three main types of record-based data models: • Relational data models • Based on mathematical concepts of relations • Use tables (or relations) to represent data and relationships • Network data models • Hierarchical data models

30. Relational Data Models • Each table consists of a fixed number of named columns (attributes) and an arbitrary number of unnamed rows (records) University Relational Data Model

31. Transforming the E-R Data Modelto the Relational Data Model • The E-R model and the relational model are actually closely related: • Entities in the E-R model become tables in the relational model • Attributes of in the E-R model are the table columns in the relational model • Relationships in the E-R model are represented by a common attribute

32. Overview • 2.1 Introduction • 2.2 Data, Information, and Metadata • 2.3 File-Based Approach • 2.4 Database Approach • 2.5 Database Development Process • 2.6 Data Models • 2.7 Summary

33. Summary • Data are known facts that can be recorded and preserved • Information is the processed data presented in a form suitable for human interpretation • Metadata is data about data • There are two approaches to convert data to information: • Traditional file-based approach • A system of files and the collection of computer programs manipulating them • Modern database approach • A database system consists of a combination of a database, a DBMS, and application programs

34. Summary (cont.) • A database is an organized collection of logically related data. • A database management system is software that allows users to define, create, and manage database access. • Database applications are computer programs that allow users to manipulate data in a DBMS through a user-friendly interface. • A database administrator (DBA) is a person or group of people responsible for all the data resources of an organization.

35. Summary (cont.) • The database development process consists of four steps: • Enterprise modeling • Conceptual database modeling • Logical database design • Physical database design and creation • The process of database development can also be explained through the schema, an overall description of the database • External schema: • Describes the database in terms of data viewed by different users • Conceptual schema: • Describes the database in terms of entities, attributes, and relationships along with integrity constraints • Internal schema: • Describes the database in terms of stored records, data fields, and indexes

36. Summary (cont.) • A data model is a collection of concepts for describing data, its relationships, and its constraints • Object-based data models use entities, attributes, and relationships to present information • The entity-relationship data model is an example of object-based model and describes data in the form of an E-R diagram • Record-based data models use records to present data • Relational data model is based on mathematical concepts of relations and is an example of record-based model

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