Database Management Systems

Instructor: Yrd. Doç. Dr. Cengiz Örencik

E-mail: cengizorencik@beykent.edu.tr

Course material http://myweb.sabanciuniv.edu/cengizo/cours

es◦ all the notes will be shared there

Course info

Not required You may use any database book

Database Management Systems – 3rd Edition◦ Ramakrishnan and Gehrke

Book

Midterm 40% Inclass quizzes (2) 10% Final 50%

Hws◦ Self study◦ Not to be graded

4

Grading

Managing data Introduction to Database design

◦ Entities, attributes, relationships, etc.◦ ER model

Relational Model◦ Representing data◦ Create, modify, query…

Relational Algebra vs. SQL Storage and Indexing Transaction Management

◦ Concurrency control◦ Crash recovery

5

Aims to learn

Database Management System (DBMS) provides….

… efficient, reliable, convenient, and safe multi-user storage of and access to massive amounts of persistent data.

Intro

Massive – terrabytes/day Persistent Safe – hard/software failure, power cut Multi-user Convenient Efficient Reliable

DBMS

A Database Management System (DBMS) is a software package designed to store and manage databases

We will not consider: Database applications may be programmed via

“frameworks”◦ Environments that help to develop program◦ Ruby on rails, Django…

DBMS may run in conjunction with “middleware”◦ Web servers that interact with database

Data-intensive applications may not use DBMS at all◦ Store everything on files

DBMS

Data independence ◦ Application programs don’t need details of data representation and

storage Efficient access

◦ A variety of techniques Data integrity and security

◦ Enforce constraints, access control… Uniform data administration

◦ How different groups of users use it◦ Organized to minimize redundancy

Reduced application development time◦ DBMS support most common important functions

Concurrent access, recovery from crashes◦ Multiple users use it without conflict◦ Protect from effects of system failures

Why Use a DBMS?

Data described as a set of records

Example: Student information in a university

Students(sid: integer, name: string, mail: string, age: integer, gpa: real)

Relational Model

Sid Name Mail Age Gpa53666 Jone jone@cs 20 3.253680 Smith smith@cs 21 2.953442 Smith smith@mat

h19 3.85

53123 Alice alice@ee 21 3.5

Relation student Each column attributes

Each row is a record that describes a student

Integrity constraints◦ Sid must be unique

Relational model

What is the name of the student with sid 53680?

How many students are enrolled to DBMS course?

What fraction of students of DBMS course get a grade better than BB?

Queries

DBMS implementer◦ Builds the system◦ Works for IBM or Oracle

Database designer◦ Interact users◦ Establishes the schema - relations◦ How to structure – how to store

Database application developer◦ Builds the programs that operate on the database◦ Use tools DBMS provides◦ Usually not computer professionals

Database administrator◦ loads the data, keep it running

Key People

DBMS used to maintain, query large datasets

Benefits include recovery from system crashes, concurrent access, quick application development, data integrity and security

DBAs hold responsible jobs and are well paid

Whether you know it or not, you’re using a database every hour

Summary