Introduction to Database Systems Ch. 1, Ch. 2 Mr. John Ortiz Dept. of Computer Science University of Texas at San Antonio

Lecture 1Introduction2 Teaching Staff  Instructor: Mr. John Ortiz Office: TBD Phone: NULL Office hour: 6 – 7pm, T & R, after any class  TA: NULL

Lecture 1Introduction3 Communication  Web page of Dr. Zhang: -use as a GUIDE ONLY  Contains everything about the course: syllabus, announcement, assignments, project, lecture notes, etc.  Generally, I will use Dr. Zhang’s outline, but do not expect my tests to look like any of his  Mailing list:

Lecture 1Introduction4 Textbooks  Required textbook: Fundamentals of Database Systems, 3 rd Edition, by R. Elmasri & S. Navathe  Recommended textbook: Oracle8 Programming, A Primer, by R. Sunderraman  Other books: Reserved in JPL under instructor’s name

Lecture 1Introduction5 Other Texts  A First Course in Database Systems, by Jeff Ullman and Jennifer Widom  Database Implementation, by Hector Garcia-Molina, Jeff Ullman and Jennifer Widom  Database Management Systems, 2 nd Ed., by Ramakrishnan & Gehrke  Database System Concepts, 3 rd Ed., by Silberschatz, Korth & Sudarshan  More …, Reserve Desk, JPL

Lecture 1Introduction6 The Study of Databases  Several aspects:  Modeling and design of databases  Database programming: querying and update operations  Database implementation  Database study cuts across many fields of Computer Science: OS, languages, AI, Logic, multimedia, theory,... ?

Lecture 1Introduction7 Course Outline  From a user perspective  Basic concepts: database, DBMS, …  Data modeling: ER, relational, OO, …  Database design: logical & physical design  Use of databases: query, update, loading, …  Database applications: design, implementing  From a system perspective  Data storage: device, structure, access, …  Query processing, optimization  Transaction processing, and more …

Lecture 1Introduction8 Course Outline  Data Modeling  ODL (Object-oriented Design Language)  Entity-Relationship Model  Relational Model  Relational Algebra  ODL/ER to Relation transformation  SQL (Standard Query Language)  Query, View, Constraints  Embedded SQL, PL/SQL

Lecture 1Introduction9 Course Outline (cont.)  Storage & Indexing  Query evaluation & Optimization  Transaction Processing  Crash Recovery  Concurrency Control  Advanced Issues (time permitting)  Web-based data processing  XML, semi-structured data  …

Lecture 1Introduction10 Prerequisite  Programming (either C/C++ or Java)  Unix operating system  Data structure & algorithm  Mathematics (logic, sets, algebra, …)

Lecture 1Introduction11 Requirements  Read, read, read  Textbooks, System manual, …  Practice, practice, practice  Homework, project  Play with sample programs, examples in books, your own ideas, …  Communicate, communicate, communicate  With instructor, TA, each other, …  Be honest  No cheating, plagiarism, …

Lecture 1Introduction12 Grading  Assignments 150 pts  Project 200 pts  Midterm I 150 pts  Midterm II 150 pts  Final Exam 300 pts  Intangibles 50 pts

Lecture 1Introduction13 The Course Project  Goal  Develop a realistic database application  Gain experience in team work  Topic?  Your choice with my approval, be creative  Team  4 members, elect a leader, complete self- organizing, collaboration, overcome differences  Milestones  Progress in 5 parts

Lecture 1Introduction14 What is a Database System? Database System = Database + DBMS  A Database is  A large, integrated collection of data  Models a real-world enterprise.  Entities (e.g., students, courses)  Relationships (e.g., Mary takes CS123)  A Database Management System (DBMS) is a software package designed to store and manage databases easily and efficiently.

Lecture 1Introduction15 Why Use a DBMS? Suppose we need to build a university information system. How do we  store the data? (use file structures…)  query the data? (write programs…)  Update data safely? (more programs…)  provide different views on the same data? (registrar versus students) (more prog…)  deal with crashes? (more prog…) Way too complicated! Go buy a DBMS!

Lecture 1Introduction16 What Does a DBMS Offer?  Efficient data storage.  Abstract data model.  Query & data manipulation language.  Different views of the data.  Data integrity & security.  Support application development.  Concurrent access by multiple users.  Crash recovery.  Data analysis, mining, visualization, …

Lecture 1Introduction17 How to Use a DBMS  Requirements modeling (conceptual)  Decide what entities should be part of the application and how they are related  Schema design and database creation  Decide on a database schema  Define the schema to the DBMS  Load data into the database  Access to data  Use a database language  Write database application programs  Use database application programs

Lecture 1Introduction18 Data Model & DB Schema  A data model is a collection of concepts for describing data in a DB, including  Objects  Relationships among objects  Constraints on objects & relationships  Operations on objects & relationships  A schema is a description of a particular collection of data, using a given data model.  An instance is a particular set of data in the DB.

Lecture 1Introduction19 Entity-Relationship Model  A popular conceptual model.  Concepts include entities, relationships, constraints. (see p.63 in text) Courses Enrolled SIDName CID Credits m n Students Age GPA Cname Grade

Lecture 1Introduction20 Relational Model  The most widely used logical model today.  Concepts include: tables, constraints, operations, … Students(sid: string, name: string, login: string, age: integer, gpa:real) Courses(cid: string, cname:string, credits:integer) Enrolled(sid:string, cid:string, grade:string)

Lecture 1Introduction21 Abstract levels of DB Schema  Views describe how users see the data.  Conceptual schema defines logical structure using a data model  Physical schema describes the files and indices used. Physical Schema Conceptual Schema View 1View 2View 3

Lecture 1Introduction22 Example: University Database  A View for registrar office Course_info(cid:string,enrollment:integer)  The conceptual schema: Students(sid: string, name: string, login:string, age: integer, gpa:real) Courses(cid: string, cname:string, credits:integer) Enrolled(sid:string, cid:string, grade:string)  the physical schema:  Relations stored as unordered files.  Index on first column of Students.

Lecture 1Introduction23 Data Independence  DBMS is able to hide details of lower level schema from clients of higher level schema  Logical data independence: Protects views from changes in logical (conceptual) structure of data.  Physical data independence: Protects conceptual schema from changes in physical structure of data.  One of the most important benefits of using a DBMS!

Lecture 1Introduction24 Database Language  Data Definition Language (DDL). Used to define & change database schemas.  Storage Definition Language (SDL). Specify the physical schema.  View Definition Language (VDL). Used to represent information to users.  Data Manipulation Language (DML). Used to query & update data.

Lecture 1Introduction25 Who Are Happy w/ Databases?  DBMS implementers (???)  End users and DBMS vendors  DB application programmers  E.g. smart webmasters  Database administrator (DBA)  Designs logical /physical schemas  Handles security and authorization  Data availability, crash recovery  Database tuning as needs evolve Must understand how a DBMS works!

Lecture 1Introduction26 Structure of a DBMS  A typical DBMS has a layered architecture.  The figure does not show the concurrency control and recovery components.  This is one of several possible architectures; each system has its own variations. Query Optimization and Execution Relational Operators Files and Access Methods Buffer Management Disk Space Management DB These layers must consider concurrency control and recovery

Lecture 1Introduction27 Summary  DBMS used to maintain, query large datasets.  Benefits include recovery from system crashes, concurrent access, quick application development, data integrity, and security.  Levels of abstraction give data independence.  A DBMS typically has a layered architecture.  DBAs hold responsible jobs and are well-paid!  DBMS R&D is one of the broadest, most exciting areas in CS.

Lecture 1Introduction28 Look Ahead  Read from the textbook:  Chapters 1 & 2  Next Topic: ER model  Read from the textbook  Chapter 3