Introduction to Database Systems

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

References

Advantages of Database systems: storage persistence,
programming interface, transaction

management
Data Model (What is Data?)
Database Language (How to manipulate data?)
DBMS Architecture and Database System Components (How can you build a billion-dollar software, like Oracle? Or you can get it free, mySQL?)
Users classification (What you can do and what you cannot do?)

Database Overview

actually makes the current society and your life work!
Banking/Credit card

/Social Security Info…
Online shopping/booking…

largest software companies in the world.
IBM offers its relational DB2

system. With IMS, a nonrelational system, IBM is by some accounts the largest DBMS vendor in the world.
Microsoft offers SQL-Server, plus Microsoft Access for the cheap DBMS on the desktop, answered by “lite” systems from other competitors.
OpenSource: mySQL, postgreSQL

The DBMS Marketplace

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

Pre-Database Era: Stone Age of Data

Data redundancy
Data is not isolated from the access implementation (different

format…)
Multiple application (concurrent program) on the same file

File Management System Problems

to restrict access to parts of the record
Ability to control

operation usage by different users
Protection from unauthorized use
Protection from the derivation of unauthorized information

Security Problems

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.

Data Integrity

Bases
Knowledge Bases
Network

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

Advantages of Databases

Information about flights and airports; Information about ticket prices and

tickets restrictions.
Banking Systems – Data items are accounts, customers, loans, mortgages, balances, etc. Failures are not tolerable. Concurrent access must be provided
Corporate Records – Data items are: sales, accounts, bill of materials records, employee and their dependents

Early Database Applications

queries are sent to servers
Where to locate servers
Multimedia Applications
Multidatabase Applications
Data

Warehouses
It’s everywhere!!

Modern Database Applications

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

Data Administrator

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

Database Users

entities and a set of relationships between them.
Entity – a

data that pertains to, or describes some component of the enterprise
Each entity is characterized by a set of attributes
Relationship – describes an interconnection between different entities
Entity Set – a set of entities that are characterized by the same entity definition
Relationship Set – a set of relationships of the same type

A Little Design Methodology: Entity-Relationship Model