Download Introduction to Database Systems

CENG 302
Introduction to Database
Management Systems
Nihan Kesim Çiçekli
email: [email protected]
URL: http://www.ceng.metu.edu.tr/~nihan/ceng302
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CENG 302
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Instructor: Nihan Kesim Çiçekli
Office: A308
Email: [email protected]
Lecture Hours: Tue. 10:40-11:30 (IE102);
Thu. 13:40-15:30 (IE102)
• Course Web page:
http://www.ceng.metu.edu.tr/~nihan/ceng302
• Teaching Assistant: Ali Anıl Sınacı
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Text Books and References
1. Raghu Ramakrishnan, Database Management
Systems, McGraw Hill, 3rd edition, 2003 (text
book).
2. R. Elmasri, S.B. Navathe, Fundamentals of
Database Systems, 4th edition, Addison-Wesley,
2004.
3. A. Silberschatz, H.F. Korth, S. Sudarshan,
Database System Concepts, McGraw Hill, 4th
edition, 2002.
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Grading
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Assignments
Midterm 1
Midterm 2
Final Exam
20 %
25 %
25 %
30 %
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Grading Policies
• Policy on missed midterm:
– no make-up exam
• Lateness policy:
– Late assignments are penalized up to 10% per
day.
• All assignments are to be your own work.
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Course Outline
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Introduction to Relational Database Management Systems
The Relational Data Model
Relational Algebra
SQL
QBE
Entity-Relationship Model
Relational Database Design: Normalization
Secondary Storage Devices
Sequential Files
Indexed Sequential Files
Hashing
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What Is a DBMS?
 A very large, integrated collection of data.
 Models real-world enterprise.
– Entities (e.g., students, courses)
– Relationships (e.g., Tarkan is taking CENG302)
 A Database Management System (DBMS) is a
software package designed to store and manage
databases.
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Why Study Databases??
?
 Shift from computation to information
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at the “low end”: scramble to webspace (a mess!)
at the “high end”: scientific applications
 Datasets increasing in diversity and volume.
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Digital libraries, interactive video, Human Genome
project, EOS project
... need for DBMS exploding
 DBMS encompasses most of CS
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OS, languages, theory, “AI”, multimedia, logic
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Why Use a DBMS?
 Data independence and efficient access.
 Reduced application development time.
 Data integrity and security.
 Uniform data administration.
 Concurrent access, recovery from crashes.
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Data Models
 A data model is a collection of concepts for
describing data.
 A schema is a description of a particular
collection of data, using the given data model.
 The relational model of data is the most widely
used model today.
– Main concept: relation, basically a table with rows and
columns.
– Every relation has a schema, which describes the
columns, or fields.
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Example: University Database
 Conceptual schema:
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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)
 Physical schema:
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Relations stored as unordered files.
Index on first column of Students.
 External Schema (View):
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Course_info(cid:string,enrollment:integer)
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Instance of Students Relation
Students( sid: string, name: string, login: string,
age: integer, gpa: real )
sid
53666
53688
53650
name
Jones
Smith
Smith
login
jones@cs
smith@ee
smith@math
age
18
18
19
gpa
3.4
3.2
3.8
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Levels of Abstraction
 Many external schemata,
single conceptual(logical)
schema and physical
schema.
– External schemata describe
how users see the data.
– Conceptual schema defines
logical structure
– Physical schema describes the
files and indexes used.
External
Schema 1
External
Schema
2
External
Schema 3
Conceptual Schema
Physical Schema
* Schemas are defined using DDL; data is modified/queried using DML.
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Data Independence
 Applications insulated from how data is structured
and stored.
 Logical data independence: Protection from
changes in logical structure of data.
 Physical data independence: Protection from
changes in physical structure of data.
* One of the most important benefits of using a DBMS!
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These layers
must
consider
concurrency
control and
recovery
Structure of a DBMS
 A typical DBMS has a
layered architecture.
 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
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