Dbms

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  • Dbms

    1. 1. CENG 302 Introduction to Database Management Systems Nihan Kesim Çiçekli email: nihan@ceng.metu.edu.tr URL: http://www.ceng.metu.edu.tr/~nihan/ceng302
    2. 2. CENG 302 <ul><li>Instructor: Nihan Kesim Çiçekli </li></ul><ul><li>Office: A308 </li></ul><ul><li>Email : nihan@ceng.metu.edu.tr </li></ul><ul><li>Lecture Hours: Tue. 1 0 :40 - 1 1 : 3 0 (IE10 2 ); Thu. 1 3 :40 -15:30 (IE10 2 ) </li></ul><ul><li>Course Web page: http://www.ceng.metu.edu.tr/~nihan/ceng302 </li></ul><ul><li>Teaching Assistant: Ali Anıl Sınacı </li></ul>
    3. 3. Text Books and References <ul><li>Raghu Ramakrishnan, Database Management Systems, McGraw Hill, 3 rd edition, 2003 ( text book ). </li></ul><ul><li>R. Elmasri, S.B. Navathe, Fundamentals of Database Systems, 4 th edition, Addison-Wesley, 2004. </li></ul><ul><li>A. Silberschatz, H.F. Korth, S. Sudarshan, Database System Concepts, McGraw Hill, 4 th edition, 2002. </li></ul>
    4. 4. Grading <ul><li>Assignments 20 % </li></ul><ul><li>Midterm 1 25 % </li></ul><ul><li>Midterm 2 25 % </li></ul><ul><li>Final Exam 30 % </li></ul>
    5. 5. Grading Policies <ul><li>Policy on missed midterm: </li></ul><ul><ul><li>no make-up exam </li></ul></ul><ul><li>Lateness policy : </li></ul><ul><ul><li>La te assignments are penalized up to 10% per day. </li></ul></ul><ul><li>All assignments are to be your own work. </li></ul>
    6. 6. Course Outline <ul><li>Introduction to Relational Database Management Systems </li></ul><ul><li>The Relational Data Model </li></ul><ul><li>Relational Algebra </li></ul><ul><li>SQL </li></ul><ul><li>QBE </li></ul><ul><li>Entity-Relationship Model </li></ul><ul><li>Relational Database Design: Normalization </li></ul><ul><li>Secondary Storage Devices </li></ul><ul><li>Sequential Files </li></ul><ul><li>Indexed Sequential Files </li></ul><ul><li>Hashing </li></ul>
    7. 7. What Is a DBMS? <ul><li>A very large, integrated collection of data. </li></ul><ul><li>Models real-world enterprise. </li></ul><ul><ul><li>Entities (e.g., students, courses) </li></ul></ul><ul><ul><li>Relationships (e.g., Tarkan is taking C ENG302 ) </li></ul></ul><ul><li>A Database Management System (DBMS) is a software package designed to store and manage databases. </li></ul>
    8. 8. Why Study Databases?? <ul><li>Shift from computation to information </li></ul><ul><ul><li>at the “low end”: scramble to webspace (a mess!) </li></ul></ul><ul><ul><li>at the “high end”: scientific applications </li></ul></ul><ul><li>Datasets increasing in diversity and volume. </li></ul><ul><ul><li>Digital libraries, interactive video, Human Genome project, EOS project </li></ul></ul><ul><ul><li>... need for DBMS exploding </li></ul></ul><ul><li>DBMS encompasses most of CS </li></ul><ul><ul><li>OS, languages, theory, “AI”, multimedia, logic </li></ul></ul>?
    9. 9. Why Use a DBMS? <ul><li>Data independence and efficient access. </li></ul><ul><li>Reduced application development time. </li></ul><ul><li>Data integrity and security. </li></ul><ul><li>Uniform data administration. </li></ul><ul><li>Concurrent access, recovery from crashes. </li></ul>
    10. 10. Data Models <ul><li>A data model is a collection of concepts for describing data. </li></ul><ul><li>A schema is a description of a particular collection of data, using the given data model. </li></ul><ul><li>The relational model of data is the most widely used model today. </li></ul><ul><ul><li>Main concept: relation , basically a table with rows and columns. </li></ul></ul><ul><ul><li>Every relation has a schema , which describes the columns, or fields. </li></ul></ul>
    11. 11. Example: University Database <ul><li>Conceptual schema: </li></ul><ul><ul><li>Students(sid: string, name: string, login: string, </li></ul></ul><ul><ul><li> age: integer, gpa:real) </li></ul></ul><ul><ul><li>Courses(cid: string, cname:string, credits:integer) </li></ul></ul><ul><ul><li>Enrolled(sid:string, cid:string, grade:string) </li></ul></ul><ul><li>Physical schema: </li></ul><ul><ul><li>Relations stored as unordered files. </li></ul></ul><ul><ul><li>Index on first column of Students. </li></ul></ul><ul><li>External Schema (View): </li></ul><ul><ul><li>Course_info(cid:string,enrollment:integer) </li></ul></ul>
    12. 12. Instance of Students Relation <ul><ul><li>Students ( sid : string, name: string, login: string, </li></ul></ul><ul><ul><li>age: integer, gpa: real ) </li></ul></ul><ul><ul><li>sid name login age gpa </li></ul></ul><ul><ul><li>53666 Jones [email_address] 18 3.4 </li></ul></ul><ul><ul><li>53688 Smith [email_address] 18 3.2 </li></ul></ul><ul><ul><li>53650 Smith [email_address] 19 3.8 </li></ul></ul>
    13. 13. Levels of Abstraction <ul><li>Many external schemata , single conceptual(logical) schema and physical schema . </li></ul><ul><ul><li>External schemata describe how users see the data. </li></ul></ul><ul><ul><li>Conceptual schema defines logical structure </li></ul></ul><ul><ul><li>Physical schema describes the files and indexes used. </li></ul></ul><ul><li>Schemas are defined using DDL; data is modified/queried using DML . </li></ul>Physical Schema Conceptual Schema External Schema 1 External Schema 3 External Schema 2
    14. 14. Data Independence <ul><li>Applications insulated from how data is structured and stored. </li></ul><ul><li>Logical data independence : Protection from changes in logical structure of data. </li></ul><ul><li>Physical data independence : Protection from changes in physical structure of data. </li></ul><ul><li>One of the most important benefits of using a DBMS! </li></ul>
    15. 15. Structure of a DBMS <ul><li>A typical DBMS has a layered architecture. </li></ul><ul><li>This is one of several possible architectures; each system has its own variations. </li></ul>These layers must consider concurrency control and recovery Query Optimization and Execution Relational Operators Files and Access Methods Buffer Management Disk Space Management DB

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