Download Introduction to Database Systems

Introduction to Database Systems
Ch. 1, Ch. 2
Mr. John Ortiz
Dept. of Computer Science
University of Texas at San Antonio
Teaching Staff
 Instructor: Mr. John Ortiz
Office: TBD
Phone: NULL
Email: [email protected]
Office hour: 6 – 7pm, T & R, after any
class
 TA: NULL
Lecture 1
Introduction
2
Communication
 Web page of Dr. Zhang: -use as a GUIDE ONLY
http://www.cs.utsa.edu/~wzhang/cs3743/home
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: [email protected]
Lecture 1
Introduction
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Textbooks
 Required textbook:
Fundamentals of Database Systems, 3rd
Edition, by R. Elmasri & S. Navathe
 Recommended textbook:
Oracle8 Programming, A Primer, by R.
Sunderraman
 Other books:
Reserved in JPL under instructor’s name
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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 1
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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 …
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Prerequisite
 Programming (either C/C++ or Java)
 Unix operating system
 Data structure & algorithm
 Mathematics (logic, sets, algebra, …)
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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, …
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Grading
 Assignments 150 pts
 Project 200 pts
 Midterm I 150 pts
 Midterm II 150 pts
 Final Exam 300 pts
 Intangibles 50 pts
Lecture 1
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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 selforganizing, collaboration, overcome differences
 Milestones
Progress in 5 parts
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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.
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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!
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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, …
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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
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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.
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Entity-Relationship Model
 A popular conceptual model.
Concepts include entities, relationships,
constraints. (see p.63 in text)
Age
GPA
Students
SID
Lecture 1
Credits
Grade
m
Enrolled
Name
n
Courses
CID
Introduction
Cname
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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)
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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.
Lecture 1
View 1
Introduction
View 2
View 3
Conceptual Schema
Physical Schema
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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.
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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!
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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.
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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!
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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.
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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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.
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Look Ahead
 Read from the textbook:
Chapters 1 & 2
 Next Topic: ER model
 Read from the textbook
Chapter 3
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