Dbms ppt.

1. Introduction to Database Systems
By Prof. Sreenivasa Kumar
IIT MADARAS

2. COURSE LAYOUT
Week 1 : Introduction and part of E/R Model Module
Week 2 : ER Model Module
Week 3 : Relational Model Module
Week 4 : Relational Model Module
Week 5 : TRC Module and part of SQL Module
Week 6 : SQL Module
Week 7 : Indexes Module
Week 8 : Indexes Module + Query Processing Module
Week 9 : Normal Forms Module
Week 10 : Normal Forms Module
Week 11 : Transaction Processing Module
Week 12 : Transaction Processing Module

3. What Is Data ?
• Different view points:
– A sequence of characters stored in computer memory
or storage
– Interpreted sequence of characters stored in computer
memory or storage
– Interpreted set of objects
• This maybe one of the most profound questions in
computer science! It is still open and keep
evolving!!

4. Where are databases?
• You cannot avoid it and it’s everywhere!
• You can say it actually makes the current
society and your life work!
• Banking/Credit card /Social Security
Info…
• Online shopping/booking…

5. Database Definition
• A database is a collection of stored operational data used
by various applications and/or users by some particular
enterprise or by a set of outside authorized applications and
authorized users
• A DataBase Management System (DBMS) is a software
system that manages execution of users applications to
access and modify database data so that the data security,
data integrity, and data reliability is guaranteed for each
application and each application is written with an
assumption that it is the only application active in the
database.

6. Advantages of Databases
• Persistent Storage – Database not only provides persistent
storage but also efficient access to large amounts of data
• Programming Interface – Database allows users to access
and modify data using powerful query language. It
provides flexibility in data management
• Transaction Management – Database supports a
concurrent access to the data

7. Pre-Database Era: Stone Age of Data
• Imagine you want build an online shopping website
– Maintain products/categories (price, picture, properties, …)
– Customers accounts
• File is uninterpreted, unstructured collection of information
• File operations: delete, catalog, create, rename, open, close,
read, write, find, …
• Access methods: Algorithms to implement operations
along with internal file organization
• Examples: File of Customers, File of Products; Access
method: implementation of a set of operations on those
files

8. Data Integrity
• A database constraint is a logical constraint about the data
expressed in a logical language.
– STUDENT.AGE >15
– If (STUDENT.CLASS ==cs43005) then
(STUDENT.PRIOR_CLASS ==cs31001)
• Database is consistent if data at each time satisfies all
integrity constraints.
• Input to any application is a set of consistent data. An
application output is a set of consistent data.

9. Database
Languages
SELECT Chair
FROM Faculty, Department
WHERE Faculty.name = “Ken Noname”
AND Faculty.Dept = Department.Dept
Data definition language (DDL) ~ like type definitions in C or C++
Data Manipulation Language (DML)
Query (SELECT)
UPDATE < relation name >
SET <attribute> = < new-value>
WHERE <condition>
Facult
y
Nam
e
De
pt
Departme
nt
De
pt
Cha
ir
S
QL

10. Data Definition Language
• Specification notation for defining the database
schema
– E.g.
create table account (
account-number char(10),
balance integer)
• DDL compiler generates a set of tables stored in a
data dictionary
• Data dictionary contains metadata (i.e., data about
data)
– database schema
– Data storage and definition language
• language in which the storage structure and access methods
used by the database system are specified
• Usually an extension of the data definition language

11. Data Administrator
• Coordinates all the activities of the database
system; the database administrator has a good
understanding of the enterprise’s information
resources and needs.
• Database administrator's duties include:
– Schema definition
– Storage structure and access method definition
– Schema and physical organization modification
– Granting user authority to access the database
– Specifying integrity constraints
– Acting as liaison with users
– Monitoring performance and responding to
changes in requirements

12. Database Users
• Naïve – do not know about database too much, invoke
application programs that are prepared already
• Application Programmers – know how to interact with the
system but may not know how DBMS is designed
• Sophisticated users that know advanced use of the system
and can use the system and packages on the top of the
system
• DBMS system users – write specialized database
applications that do not fit into the traditional data
processing framework

13. References
• A. Silberschatz, H. F. Korth, S Sudarshan,
Database System Concepts, 5th Ed., McGrow Hill, 2005
http://www.db-book.com
• Hector Garcia-Molina, Jeffrey D. Ullman, Jennifer Widom,
Database Systems, The Complete Book, Prentice Hall, 2002
http://www-db.stanford.edu/~ullman/dscb.html
• Class notes

14. THANK
YOU