Lecture 1 On Fundamentals Of Database Systems PDF

Faculty Of Computer Science Mohamed Ghoneimy , Ph.D. [email protected] Copyright © 2016, 2011, 2007 Pearson Education, Inc. All Rights Reserved About me.. And you. Copyright © 2016, 2011, 2007 Pearson Education, Inc. All Rights Reserved Simple Agreements C...

Faculty Of Computer Science Mohamed Ghoneimy , Ph.D. [email protected] Copyright © 2016, 2011, 2007 Pearson Education, Inc. All Rights Reserved About me.. And you. Copyright © 2016, 2011, 2007 Pearson Education, Inc. All Rights Reserved Simple Agreements Copyright © 2016, 2011, 2007 Pearson Education, Inc. All Rights Reserved Fundamentals Of Database Systems CS 215 Lecturer1: Introduction Fundamental Database Concepts Copyright © 2016, 2011, 2007 Pearson Education, Inc. All Rights Reserved Fundamentals of Database Systems Seventh Edition Chapter 1 Databases and Database Users Copyright © 2016, 2011, 2007 Pearson Education, Inc. All Rights Reserved Types of Databases and Database Applications Traditional Applications: – Numeric and Textual Databases More Recent Applications: – Multimedia Databases – Geographic Information Systems (GIS) – Biological and Genome Databases – Data Warehouses – Mobile databases – Real-time and Active Databases In this course we focus on traditional applications Copyright © 2016, 2011, 2007 Pearson Education, Inc. All Rights Reserved Recent Developments (1 of 2) Social Networks started capturing a lot of information about people and about communications among people- posts, tweets, photos, videos in systems such as: – Facebook – Twitter – Linked-In All of the above constitutes data Search Engines- Google, Bing, Yahoo : collect their own repository of web pages for searching purposes Copyright © 2016, 2011, 2007 Pearson Education, Inc. All Rights Reserved Basic Definitions Database: – A collection of related data. Data: – Known facts that can be recorded and have an implicit meaning. Mini-world: – Some part of the real world about which data is stored in a database. For example, student grades and transcripts at a university. Database Management System (DBMS): – A software package/ system to facilitate the creation and maintenance of a computerized database. Database System: – The DBMS software together with the data itself. Sometimes, the applications are also included. Copyright © 2016, 2011, 2007 Pearson Education, Inc. All Rights Reserved Impact of Databases and Database Technology Businesses: Banking, Insurance, Retail, Transportation, Healthcare, Manufacturing Service Industries: Financial, Real-estate, Legal, Electronic Commerce, Small businesses Education: Resources for content and Delivery More recently: Social Networks, Environmental and Scientific Applications, Medicine and Genetics Personalized Applications: based on smart mobile devices Copyright © 2016, 2011, 2007 Pearson Education, Inc. All Rights Reserved Figure 1.1 Simplified database system environment Copyright © 2016, 2011, 2007 Pearson Education, Inc. All Rights Reserved Typical DBMS Functionality Define a particular database in terms of its data types, structures, and constraints Construct or Load the initial database contents on a secondary storage medium Manipulating the database: – Retrieval: Querying, generating reports – Modification: Insertions, deletions and updates to its content – Accessing the database through Web applications Processing and Sharing by a set of concurrent users and application programs – yet, keeping all data valid and consistent Copyright © 2016, 2011, 2007 Pearson Education, Inc. All Rights Reserved Application Activities Against a Database Applications interact with a database by generating – Queries: that access different parts of data and formulate the result of a request – Transactions: that may read some data and “update” certain values or generate new data and store that in the database Applications must not allow unauthorized users to access data Applications must keep up with changing user requirements against the database Copyright © 2016, 2011, 2007 Pearson Education, Inc. All Rights Reserved Additional DBMS Functionality DBMS may additionally provide: – Protection or Security measures to prevent unauthorized access – “Active” processing to take internal actions on data – Presentation and Visualization of data – Maintenance of the database and associated programs over the lifetime of the database application ▪ Called database, software, and system maintenance Copyright © 2016, 2011, 2007 Pearson Education, Inc. All Rights Reserved Example of a Database (with a Conceptual Data Model) (1 of 2) Mini-world for the example: – Part of a UNIVERSITY environment. Some mini-world entities: – STUDENTs – COURSEs – SECTIONs (of COURSEs) – (academic) DEPARTMENTs – INSTRUCTORs Copyright © 2016, 2011, 2007 Pearson Education, Inc. All Rights Reserved Example of a Database (with a Conceptual Data Model) (2 of 2) Some mini-world relationships: – SECTIONs are of specific COURSEs – STUDENTs take SECTIONs – COURSEs have prerequisite COURSEs – INSTRUCTORs teach SECTIONs – COURSEs are offered by DEPARTMENTs – STUDENTs major in DEPARTMENTs Note: The above entities and relationships are typically expressed in a conceptual data model, such as the ENTITY-RELATIONSHIP data model (see Chapters 3, 4) Copyright © 2016, 2011, 2007 Pearson Education, Inc. All Rights Reserved Figure 1.2 Example of a simple database (1 of 4) COURSE Course_name Course_number Credit_hours Department Intro to Computer CS1310 4 CS Science Data Structures CS3320 4 CS Discrete Mathematics MATH2410 3 MATH Database CS3380 3 CS Copyright © 2016, 2011, 2007 Pearson Education, Inc. All Rights Reserved Figure 1.2 Example of a simple database (2 of 4) SECTION Section_identifier Course_number Semester Year Instructor 85 MATH2410 Fall 07 King 92 CS1310 Fall 07 Anderson 102 CS3320 Spring 08 Knuth 112 MATH2410 Fall 08 Chang 119 CS1310 Fall 08 Anderson 135 CS3380 Fall 08 Stone Copyright © 2016, 2011, 2007 Pearson Education, Inc. All Rights Reserved Figure 1.2 Example of a simple database (3 of 4) GRADE_REPORT Student_number Section_identifier Grade 17 112 B 17 119 C 8 85 A 8 92 A 8 102 B 8 135 A Copyright © 2016, 2011, 2007 Pearson Education, Inc. All Rights Reserved Figure 1.2 Example of a simple database (4 of 4) PREREQUISITE Course_number Prerequisite_number CS3380 CS3320 CS3380 MATH2410 CS3320 CS1310 Copyright © 2016, 2011, 2007 Pearson Education, Inc. All Rights Reserved Main Characteristics of the Database Approach (1 of 3) Self-describing nature of a database system: – A DBMS catalog stores the description of a particular database (e.g. data structures, types, and constraints) – The description is called meta-data*. – This allows the DBMS software to work with different database applications. Insulation between programs and data: – Called program-data independence. – Allows changing data structures and storage organization without having to change the DBMS access programs. Copyright © 2016, 2011, 2007 Pearson Education, Inc. All Rights Reserved Figure 1.3 Example of a simplified database catalog (1 of 2) RELATIONS Relation_name No_of_columns STUDENT 4 COURSE 4 SECTION 5 GRADE_REPORT 3 PREREQUISITE 2 Copyright © 2016, 2011, 2007 Pearson Education, Inc. All Rights Reserved Figure 1.3 Example of a simplified database catalog (2 of 2) COLUMNS Column_name Data_type Belongs_to_relation Name Character (30) STUDENT Student_number Character (4) STUDENT Class Integer (1) STUDENT Major Major_type STUDENT Course_name Character (10) COURSE Course_number XXXXNNNN COURSE …. …. …. …. …. …. …. …. …. Prerequisite_number XXXXNNNN PREREQUISITE Note: Major_type is defined as an enumerated type with all known majors. XXXXNNNN is used to define a type with four alphabetic characters followed by four numeric digits. Copyright © 2016, 2011, 2007 Pearson Education, Inc. All Rights Reserved Main Characteristics of the Database Approach (2 of 3) 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 of 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. Copyright © 2016, 2011, 2007 Pearson Education, Inc. All Rights Reserved Main Characteristics of the Database Approach (3 of 3) Sharing of data and multi-user transaction processing: – Allowing a set of concurrent users to retrieve from and to update the database. – Concurrency control within the DBMS guarantees that each transaction is correctly executed or aborted – Recovery subsystem ensures each completed transaction has its effect permanently recorded in the database – OLTP (Online Transaction Processing) is a major part of database applications. This allows hundreds of concurrent transactions to execute per second. Copyright © 2016, 2011, 2007 Pearson Education, Inc. All Rights Reserved Database Users Users may be divided into – Those who actually use and control the database content, and those who design, develop and maintain database applications (called “Actors on the Scene”), and – Those who design and develop the DBMS software and related tools, and the computer systems operators (called “Workers Behind the Scene”). Copyright © 2016, 2011, 2007 Pearson Education, Inc. All Rights Reserved Database Users – Actors on the Scene (1of 2) Actors on the scene – Database administrators: ▪ Responsible for authorizing access to the database, for coordinating and monitoring its use, acquiring software and hardware resources, controlling its use and monitoring efficiency of operations. – Database Designers: ▪ Responsible to define the content, the structure, the constraints, and functions or transactions against the database. They must communicate with the end-users and understand their needs. Copyright © 2016, 2011, 2007 Pearson Education, Inc. All Rights Reserved Database End Users (1 of 2) Actors on the scene – End-users: They use the data for queries, reports and some of them update the database content. End-users can be categorized into: ▪ Casual: access database occasionally when needed ▪ Naïve or Parametric: they make up a large section of the end-user population. – They use previously well-defined functions in the form of “canned transactions” against the database. – Users of Mobile Apps mostly fall in this category – Bank-tellers or reservation clerks are parametric users who do this activity for an entire shift of operations – Social Media Users post and read information from websites Copyright © 2016, 2011, 2007 Pearson Education, Inc. All Rights Reserved Database End Users (2 of 2) Sophisticated: – These include business analysts, scientists, engineers, others thoroughly familiar with the system capabilities. – Many use tools in the form of software packages that work closely with the stored database. Stand-alone: – Mostly maintain personal databases using ready-to-use packaged applications. – An example is the user of a tax program that creates its own internal database. – Another example is a user that maintains a database of personal photos and videos. Copyright © 2016, 2011, 2007 Pearson Education, Inc. All Rights Reserved Database Users – Actors on the Scene (2 of 2) System Analysts and Application Developers This category currently accounts for a very large proportion of the IT work force. – System Analysts: They understand the user requirements of naïve and sophisticated users and design applications including canned transactions to meet those requirements. – Application Programmers: Implement the specifications developed by analysts and test and debug them before deployment. – Business Analysts: There is an increasing need for such people who can analyze vast amounts of business data and real-time data (“Big Data”) for better decision making related to planning, advertising, marketing etc. Copyright © 2016, 2011, 2007 Pearson Education, Inc. All Rights Reserved Database Users – Actors behind the Scene System Designers and Implementors: Design and implement DBMS packages in the form of modules and interfaces and test and debug them. The DBMS must interface with applications, language compilers, operating system components, etc. Tool Developers: Design and implement software systems called tools for modeling and designing databases, performance monitoring, prototyping, test data generation, user interface creation, simulation etc. that facilitate building of applications and allow using database effectively. Operators and Maintenance Personnel: They manage the actual running and maintenance of the database system hardware and software environment. Copyright © 2016, 2011, 2007 Pearson Education, Inc. All Rights Reserved Advantages of Using the Database Approach (1 of 2) Controlling redundancy in data storage and in development and maintenance efforts. – Sharing of data among multiple users. Restricting unauthorized access to data. Only the DBA staff uses privileged commands and facilities. Copyright © 2016, 2011, 2007 Pearson Education, Inc. All Rights Reserved Advantages of Using the Database Approach (2 of 2) Providing optimization of queries for efficient processing. Providing backup and recovery services. Providing multiple interfaces to different classes of users. Representing complex relationships among data. Enforcing integrity constraints on the database. Drawing inferences and actions from the stored data using deductive and active rules and triggers. Copyright © 2016, 2011, 2007 Pearson Education, Inc. All Rights Reserved Additional Implications of Using the Database Approach (1 of 2) Potential for enforcing standards: – This is very crucial for the success of database applications in large organizations. Standards refer to data item names, display formats, screens, report structures, meta-data (description of data), Web page layouts, etc. Reduced application development time: – Incremental time to add each new application is reduced. Copyright © 2016, 2011, 2007 Pearson Education, Inc. All Rights Reserved Additional Implications of Using the Database Approach (2 of 2) Flexibility to change data structures: – Database structure may evolve as new requirements are defined. Availability of current information: – Extremely important for on-line transaction systems such as shopping, airline, hotel, car reservations. Economies of scale: – Wasteful overlap of resources and personnel can be avoided by consolidating data and applications across departments. Copyright © 2016, 2011, 2007 Pearson Education, Inc. All Rights Reserved