The Database Environment

IST359 M005

Yang Wangywang@syr.edu342 Hindshttp://blackboard.syr.edu

Acknowledgements and caveat

These slides draw liberally, with permission, from the following sources:

• IST359 materials by Prof. Michael Fudge Jr.

Caveat (beware): At best, PowerPoint slides are only a pale limitation of the entirety of a class meeting. In IST359 in particular, the lectures will cover topics beyond what appears in these slides. Don’t rely on them as a substitute for attending class.

Teaching Assistant

Zhiheng Mai

zmai@syr.edu

Learning Objectives

• Concretize the concepts of data, information, data management and metadata

• Explain what a database is and why databases are important• Describe a database management system• Differentiate between the DBMS and a database• Describe the different data models and abstraction layers• Explain the similarities and differences among DBMS products• Explain DBMS history and modern uses• Describe how data is physically stored in primary and

secondary storage

Before we begin…What’s…

Data?

Information?

Data Management?

Metadata?

Query?

Data or Information?

Where’s theData?

Where’s the

Metadata?

Where is the:

Data?Meta-Data?

Activity: Data or Meta-Data?

1. A Zip Code: 132442. A Zip Code is 5 Characters XXXXX3. A List of First Names: Tom, Dick, Harry4. A Picture, Like This One:5. The Name of the Picture

file FrostTrees.jpg6. When you place an order, the quantity of the

item ordered must be a number >0

Something strange and confusing:• Data can be information:

– $5 (the amount of money in my wallet)• Information can be data:

– I calculate student final grades, then place them on a form sent to the registrar’s office.

• Metadata can be data:– The names of MP3 files in your personal

collection.

Actually it’s all about context!

What is it, part duex!

Database

Database Management System (DBMS)

Elements of a Database

Meta-Data

Data

DatabaseData-Management

Data “In”

Information “Out”

End-User

DBMS is software. It stores the data/meta data and “enables” data-management

Clarification via Family Guy

• Brian can write his novel on a typewriter or w/pen and paper.

• But there are obvious advantages to using word processing software.

• Most databases use DBMS’s just like most papers are written with word processors

Database Brian’s NovelDBMS WP Software

Is this: Database or DBMS?

Database or DBMS?

Database or DBMS?

SQL Server: Database or DBMS?

Database or DBMS?

Database or DBMS?

Database or DBMS?

Fundamental Axioms of DBMSs

• Users communicate with computer apps• Computer apps communicate with DBMSs• Users normally do not communicate with

DBMSs directly• Normally DBMSs are not used interactively• A DBMS is not a replacement for sound

database design principles.

First of many examples for the semester

• https://my.ischool.syr.edu

Db using Relational

ModelYou Website

User Interface and Business

Logic (HTML/C#)

Data access logic and

Data (SQL)

Web Browser Web Server (IIS) SQL Server

ApplicationComponents

Data or Metadata?

Database?

DBMS?

Evolution of DBMSs

Enterprise DBMS Market Share

Product ShareOracle 44.4%IBM (DB2) 21.2%Microsoft (SQL Server) 18.6%Others: (Sybase, NCR Terdata, etc…) 5.9%Open Source (MySQL, PostgreSQL, etc…) 9.9%

* Source: Computerworld 2007

DBMS deployment plans 2008

* source: gartner

An employable skill in the future.

Source BLS: 2008http://www.bls.gov/oes/current/oes151061.htm

Data Models: Abstraction Levels

Conceptual

Internal

External

Physical

Logical

Highly AbstractHardware and Software

Independent

Somewhat Abstract Hardware IndependentSoftware Dependent

Not Abstract (Concrete)Hardware and Software Dependent

An Concrete Example• SU administration asks us to build a database for class enrollment

o E.g., student info, class info, a student enrolls in a class• Logical model: what database model to use? Relational, object-

oriented, object-relational, etc. o E.g., we use relational model (entities, relations).

• Internal model: use a DBMS to implement our relational modelo E.g., what do the student, class tables look like?

• External model: what the internal model looks like to end users (hide details of the implementation, e.g., tables)o E.g., you can see a student enrolls in a class

• Physical model: how database is implemented by the DBMSo E.g., how is the database physically stored? In a single file?

• Conceptual model: represent requirements, what needs to be represent in the database?

Elements of the DBMS Approach

• Enterprise Data Model– Graphical model showing high-level entities and relationships

for the organization• Relational Databases

– Database technology involving tables (relations) representing entities and primary/foreign keys representing relationships

• Use of Internet Technology– Networks and telecommunications, distributed databases,

client-server and 3-tier architectures• Database Applications

– Application programs used to perform database activities CRUD for database users