Riyadh Philanthropic Society For Science Prince Sultan College For Woman Dept. of Computer & Information Sciences CS 340 Introduction to Database Systems (Chapter 1: Databases and Database Users)

Chapter 1: Databases and Database Users1 Outline State Before - File Processing System Drawbacks of the File Processing System Introduction to Databases What is a Database? What is a Database Management System (DBMS)? What is a Database System? Example Characteristics of the Database Approach Database Users Advantages of Using DBMS A Brief History of Database Applications Extending Database Capabilities for New Applications Information Retreival When Not to Use a DBMS Reading: Chapter 1

Chapter 1: Databases and Database Users 2 State Before - File Processing System In the early days, database applications were built on top of file systems.

Chapter 1: Databases and Database Users 3 State Before - File Processing System Program A Program B Program C Program A Program B Program A Program B Order Filing System Invoicing System Payroll System Customer Master File Inventory Master File Back Order File Inventory Pricing File Customer Master File Employee Master File Orders Department Accounting Department Payroll Department

Chapter 1: Databases and Database Users 4 Drawbacks of the File Processing System Program-data dependence: All programs maintain meta-data for each file they use. Data redundancy (Duplication of data) & inconsistency: Different systems/programs have separate copies of the same data. Limited data sharing: No centralized control of data. Lengthy development times: Programmers must design their own file formats. Excessive Program maintenance: 80% of information systems budget.

Chapter 1: Databases and Database Users 5 Solution A single repository of data should be maintained that is defined once and then accessed by various users (i.e. Database approach).

Chapter 1: Databases and Database Users 6 Introduction to Databases Databases touch all aspects of our lives. Examples: Banking: all transactions. Hotels: reservation. Airlines: reservation, schedules. Libraries: catalog. Universities: registration, grades. Sales: customers, products, purchases. Manufacturing: production, inventory, orders. Human resources: employee records, salaries. Traditional database applications Most of the information is either textual or numeric.

Chapter 1: Databases and Database Users 7 Types of Database Applications Traditional databases (textual & numeric databases). Multimedia databases. Geographic Information System (GIS). Data warehouses & OnLine Analytical Processing (OLAP). Real-time & active databases.

Chapter 1: Databases and Database Users What is a Database? A collection of related data. Has the following implicit properties: Represents some aspects of the real world. (Sometimes called the miniworld) Is logically coherent collection of data. Is designed for specific purpose and intended users. Can be at varying size and complexity. Can be generated and maintained manually or it may be computerized. 8 Known facts that can be recorded and that have implicit meaning. E.g. names, telephone numbers, addresses.

Chapter 1: Databases and Database Users What is a Database Management System (DBMS)? A collection of programs that enables users to create and maintain a database. Facilitates the process of: Defining: specifying data types, structures, & constraints for data. Constructing: the process of storing the data itself. Manipulating: querying the database to retrieve or update data and generating reports from the data. Sharing: accessing the database concurrently. databases among various users and applications. Protects the database and maintains it over a long period of time. Examples: Oracle, MS Access, DB2, Informix, MySQL, SyBase. 9

Chapter 1: Databases and Database Users What is a Database System? Is the combination of the database and the DBMS software. 10

Chapter 1: Databases and Database Users A Simplified Database System Environment Stored Database Definition (Meta-Data) Stored Database Application Programs/Queries Software to Process Queries/Programs Software to Access Stored Data Users/Programmers DBMS Software Database System 11

Chapter 1: Databases and Database Users Example STUDENTNameStudentNumberClassMajor Smith171CS Brown82CS COURSECourseNameCourseNumberCreditHoursDepartment Discrete MathematicsMATH24103MATH DatabaseCS33804CS SECTIONSectionIDentifierCourseNumberSemesterYear 85MATH2410Fall03 135CS3380Fall04 Instructor Anderson Stone GRADE_REPORTStudentNumber 17 SectionIDentifier Grade A B 8135A PREREQUISITECourseNumber MATH222 CS3380 PrerequisiteNumber MATH211 CS Record Field

Chapter 1: Databases and Database Users Characteristics of the Database Approach Self-describing nature of a database system: A DBMS catalog stores the description of the database (the description is called meta-data). This allows the DBMS software to woks with different databases. Insulation between programs (Program-data independence): Allows changing data storage structures and operations without having to change the DBMS access programs. Relations Columns 13 Relation_nameNo_of_columnsColumn_nameData_type STUDENT4NameCharacter (30) COURSE4StudentNumberCharacter (4) …… PREREQUISITE2 Belongs_to_relation STUDENT …… PrerequisiteNumberXXXXNNNN … PREREQUISITE

Chapter 1: Databases and Database Users Characteristics of the Database Approach Data abstraction: A data model is used to hide storage details and present the users with a conceptual view of the database. Programs refer to the data model constructs rather than data storage details. Support multiple views of the data: Each user may see a different view of the database, which describes only the data of interest to that user. Sharing of data & multi-user transaction processing: Allowing a set of concurrent users to retrieve and to update the database. Concurrency control within the DBMS guarantees that each transaction is correctly executed or completely aborted. 14

Database Users Actors behind the scene: People whose jobs are associated with the design, development, and operation of the DBMS software and system environment. They are not interested in the database itself. Include the following categories: DBMS system designers and implementers. Tool developers. Operators and maintenance personnel. Actors on the scene: People whose jobs involve the day-to-day use of a large database. Chapter 1: Databases and Database Users 15

Chapter 1: Databases and Database Users 16 Actors on the Scene - Database Administrators Manage, administer, & acquire recourses of the database & DBMS. Generate user authority to access the database. Coordinate & monitor all the activities of the database system. Manage security & poor system response time.

Chapter 1: Databases and Database Users 17 Actors on the Scene - Database Designers Identify the data to be stored in the database. Choose appropriate structure to represent & store this data. Communicate with the perspective users to understand their requirements. Interact with each potential group of users & develop views of the database.

Chapter 1: Databases and Database Users18 Actors on the Scene - End Users People whose jobs require access to the database for querying, updating, & generating reports. Causal end users: Occasionally access the database. Typically from management or other occasional browsers. Naive (parametric) users: Make up a sizable portion of the database end users. Main job involves constantly querying & updating databases using canned transactions. E.g. Bank tellers. Sophisticated users: Include people who are familiar with the DBMSs. Stand alone users: Maintain personnel databases by using ready-made program packages that provide easy menus or GUI.

Chapter 1: Databases and Database Users 19 Actors on the Scene - System Analysts & Application Programmers (Software Engineers) System analysts: Determine the requirements of end users. Develop specifications for canned transactions that meets these requirements. Application programmers: Implement these specifications as programs. Test, debug, document, and maintain these canned transactions.

Chapter 1: Databases and Database Users Advantages of Using DBMS Controlling redundancy in: data storage development and maintenance efforts. Sharing of data among multiple users. Restricting unauthorized access to data. Providing persistent storage for program objects (in object-oriented DBMS’s). Providing storage structures (e.g. indexes) for efficient query processing. 20

Chapter 1: Databases and Database Users Advantages of Using DBMS Providing Backup and recovery. Providing multiple user interfaces. Representing complex relationships among data. Enforcing integrity constraints. Permitting inferencing and actions using rules. 21

Chapter 1: Databases and Database Users Additional Implications of Using the Database Approach Potential for enforcing standards. Reduced application development time. Flexibility to change data structures. Availability of up-to-data information. Economies of scale. 22

Chapter 1: Databases and Database Users A Brief History of Database Applications Early database applications using hierarchical & network systems: Introduced in mid 1960’s. Dominated during the seventies. Some of the worldwide database processing still occurs using these models. Relational Databases: Introduced in Relational DBMS products emerged in the 1980’s 23

Chapter 1: Databases and Database Users A Brief History of Database Applications Object-Oriented applications: Introduced in late 1980’s to cater the need of complex data processing. Their use has not taken off much. Many relational DBMSs have incorporated object database concepts, leading to new category called object-relational DBMSs. Data on the web and E-commerce applications: Web contains data in HTML with links among pages. This have given rise to a new set of applications. 24

Chapter 1: Databases and Database Users Extending Database Capabilities for New Applications Examples of new applications: Storage and retrieval of images. Scientific applications. Storage and retrieval of videos. Data mining Spatial applications. Time series. Basic relational systems are not very suitable for many of these applications: More complex data structures are needed. New data types are needed. New operations and query language constructs are necessary. New storage and indexing structures are needed. This led DBMS developers to add functionality to their systems. E.g. Incorporating concepts from object-oriented databases. 25

Chapter 1: Databases and Database Users Information Retrieval (IR) Information retrieval (IR) is the science of searching for information in documents, searching for documents themselves, searching for metadata which describe documents, or searching within databases, whether relational stand-alone databases or hypertextually-networked databases such as the World Wide Web. 26

Chapter 1: Databases and Database Users When Not to Use a DBMS Unnecessary overhead costs: High initial investment in hardware, software and training. The generality that a DBMS provides for defining and processing data. Overhead for providing security, concurrency control, recovery, & integrity functions. The database and applications are simple, well defined, and not expected to change. There are stringent real-time requirements for some programs that may not be met because of DBMS overhead. Multiple-user access to data is not required. 27