Introduction to Database
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Transcript of Introduction to Database
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
Sales Files
Data entry & report
File handling routines
File definition
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 end-
users.
• 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