Introduction to Database
CIS458.101
Chapter 1
Sungchul Hong
Database System
• The most important development in the
field of software engineering.
• Database serve as the foundation for
considerable progress in the basic science
fields ranging from computing to biology.
Introduction
• Database
– A collection of related data.
• DBMS (Database Management System)
– The software that manages and controls access
tot the database.
• Database application
– A program that interacts with the database at
some point in its execution.
Examples of Databases
• Supermarket
– Inventory
– Customer service
•
•
•
•
Credit card
Booking a ticket at the travel agents
Using the local library
University
Traditional File-Based Systems
• Each program defines and manages its own
data.
• Separation and isolation of data
• Duplication of data
• Data dependence
• Incompatibility of files
• Fixed queries of application program
Database Approach
• A shared collection of logically related data,
and a description of this data, designed to
meet the information needs of an
organization.
• System catalog (data dictionary)
• Program-data independence.
File-Based System
Data
entry
&
report
File
handling
routines
File
definition
Sales Files
The Database Management
System (DBMS)
• A software system that enables users to define,
create, maintain, and control access to the
database.
• Data Definition Language(DDL)
• Data Manipulation Language (DML)
– Structured Query Language (SQL)
• Views
– Level of security, customization, provide consistent
structure
Components of the DBMS
Environment
• Hardware
– Client-server architecture
– Backend, front end
• Software
– DBMS, application programs, SQL
• Data
– Operational data, meta data
• Procedure
– Instructions and rules
• People
Roles in the Database
Environment
• Data Administrator (DA)
– Responsible for the management of the data resource
including database planning, development and
maintenance of standards, policies, and procedures, and
conceptual/logical database design.
• Database Administrator (DBA)-more technical
– Responsible for the physical realization of the database,
including physical database design and implementation,
security and integrity of the application users.
Roles in the Database
Environment (2)
• Database Designer
– Logical database designer
• Identifying the data, relationship between the data, and the
constraints on the data.
• Business rules.
– Physical database designer
• Mapping the logical database design into a set of tables and
integrity constraints.
• Selecting specific storage structures
• Designing security measures required on the data
Roles in the Database
Environment (3)
• Application Developer
– Provide the required functionality for the endusers.
• End-Users
– Naïve users
– Sophisticated users.
Data Redundancy
Advantages of DBMS
•
•
•
•
•
•
•
Control of data redundancy
Data consistency
More information from the same amount of data
Sharing of data
Improved data integrity
Improved security
Enforcement of standards
Advantages of DBMS (2)
•
•
•
•
•
•
•
Economy of scale
Balance of confliction requirements
Improved data accessibility and responsiveness
Increased productivity
Improved maintenance through data independence
Increased concurrency
Improved backup and recovery services
Disadvantages of DBMS
•
•
•
•
•
•
•
Complexity
Size
Cost of DBMS
Additional hardware costs
Cost of conversion
Performance
Higher impact of a failure
History of DBMS
• Apollo moon-landing project (1960s)
– GUAM (Generalized Update Access Method)
– Hierarchical structure
• IMS (Information Management System) (mid
1960s)
– Serial storage
– device (Tape recorder)
• IDS (Integrated Data Store) (mid 1960s)
– Network DBMS
• CODASYL (Conference on Data Systems
Languages)
History of DBMS
• DBTG (Data Base Task Group) – 1967
• Relational Model – E. F. Codd, 1970
– R
– SQL
– DB2, SQL/DS, Oracle
• INGRES II, Informix, Access, FoxPro, Paradox,
Interbase, and R:Base
• ER model – Chen, 1979
– Semantic data modeling
• Object-Oriented DBMS, Object-Relational DBMS
Descargar

Introduction to Database