Transcript Presentation2

Presentation by: Veselin Tsvetkov
ID#: 100031146
 An
overview of Database Management
 Database
 DBMS
 Database Systems
 Why use database?
 Database architecture
 An example of the Three Levels
 Schema
 Data Independence
 Types of Database Models
 Database design phases
 Data:
Known facts that can be recorded
and that have implicit meaning
 Database: Collection
of related data
• Ex. the names, telephone numbers and
addresses of all the people you know
 Database
Management System: A
computerized record-keeping system
 Goals
of a Database Management
System:
• To provide an efficient as well as a convenient
environment for accessing data in a database;
• Enforce information security: database security,
concurrency control, crash recovery
 It is a general purpose
• Defining database
• Constructing database
• Manipulating database
facility for:
 1960
– First DBMS designed by Charles
Bachman at GE. IBMs Information
Management System (IMS)
 1970 – Codd introduced the RDBMS
 1980 – Relational model became popular
and accepted as the main database
paradigm. SQL, ANSI SQL, etc.
 1980 to 1990 – New data models, powerful
query languages, etc. Popular vendors are
Oracle, SQL Server, IBMs DB2, Informix, etc.




Various types of data: Images, Text,
complex queries, Data Mining, etc.
Enterprise Resource Planning (ERP)
Management Resource Planning (MRP)
Database in Web technologies
Current Database trends:
 Multimedia databases
 Interactive video
 Streaming data
 Digital libraries






Data Definition
Data Manipulation
Data Security and Integrity
Data Recovery and Concurrency
Data Dictionary
Performance
Catalog in DBMS. Data definition in
file systems is part of application
programs.
 Program-Data independence
 Views
 Sharing and Transaction
processing

Program-1
Data description-1
Program-2
Data description-2
Program-3
Data description-3
File-1
File-2
File-3
File System Approach
Application program-1
with data semantics
Application program-2
with data semantics
Application program-3
with data semantics
Description
Manipulation
Control
……
…
DBMS Approach
Database
 Redundancy
can be reduced
 Inconsistency can be avoided
 Data can be shared
 Standards can be enforced
 Security restrictions can be applied
 Integrity can be maintained
 Data independence can be provided
 Backup and Recovery
 Data
Model
• A data model is a collection of high-level data
description constructs that hide many low-level
storage details
 Relational
Data Model
 Semantic Data Model – ER Model
A
relation is a set of records and
attributes. Also known as tuples and
columns.
A
schema is the description of data in
terms of a data model
• Eg. Student (RegNo: String, Name: String, Sem:
Integer, Branch: String)
RegNo
Name
Sem
Branch
100031146
Veselin
Tsvetkov
3
COS
100029152
John Bush
4
INF
100014839
Petar Georgiev
5
JMC
 Relational
Model – DB2, Oracle, Informix,
Sybase, MS-Access, Foxbase, Paradox, etc.
 Hierarchical Model – IMS DBMS
 Network Model – IDS & IDMS
 Object-Oriented Model – ObjectStore &
Versant
 Object-Relational Model – Products from IBM,
Oracle, ObjectStore, Versant
External Schema - 1
External Schema - 2
Conceptual Schema
Physical Schema
External Schema - 3


Describes the stored data in terms of the data model
of the DBMS. This leads to conceptual database
design.
Examples:
Student: (RegNo: Integer, Name: String, Sem: Integer,
Branch: String)
Faculty: (Fid: Integer, Fname: String, Salary: Float)
Course: (SecID: Integer, CourseNo: Integer, Sem:
Integer, Year: Integer, Instructor: String)
GradeReport: (RegNo: Integer, SecID: Integer, Grade:
Char)



Describes the actual storage details of
the relations described in conceptual
schema.
Primary indexing, sequential, binary,
secondary indexing, etc.
This leads to the physical database
design
 Describes
several views of the database
based on the database model.
 Several external schemas are possible for a
single database.
 Each view is based upon the user
requirements.
Example:
StdGrade: (RegNo: Integer, Name: String, Sem:
Integer, Grade: Char)
 The
data independence is the ability to
change the schema at one level of a
database system with out changing the
schema at a higher level.
 Logical
data Independence
It is the ability to change the schema at one
level of a database system without changing
the external schema or application
programs, is called as the logical data
independence. With out changing the
application programs, one can change the
logical schema.
Suppose the Faculty relation is modified as
follows:
Faculty_Public(Fid:Integer, FName:String,
Office:Integer)
Faculty_Private(Fid:Integer, Salary:Float)
Any view designed before this
modification can still retrieve the data
with little modification (relation name)
and obtain the same answer.


There are occasions for changing the
internal structures for improved
performance of the retrieval of data.
Any change introduced to the internal
schema or physical schema will not affect
the other schemas.
 DDL
– Data Definition Language
 SDL
– Storage Definition Language
 VDL
– View Definition Language
 DML
– Data Manipulation Language
(For data manipulations like
insertion, deletion, update,
retrieval, etc.)
 Atomic
operation – Handling concurrent
execution of transactions from several
users.
 Example: Reservation systems, Banking
systems.
 Transaction
failures and recovery.
 Locking protocols.
 Log (WAL – Write Ahead Log)
Web Forms
Front-End
SQL I/f
SQL Commands
Plan Executor
Parser
Operator Evaluator
Optimizer
Tx
Manager
Lock
Manager
Files & Access
Buffer Manager
SQL Engine
Recovery
Manager
Disk Space Manager
Data File
Catalog
Database
DBMS
THANK YOU FOR YOUR ATTENTION!