Transcript Introduction to Database

Introduction to Database
Introduction to Database
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Dept. of Multimedia, KEUKDONG College
Introduction to Database
Contents
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Introduction to Database
History of RDBMS
Entity-Relationship Modeling
Database Language
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Dept. of Multimedia, KEUKDONG College
Introduction to Database
Introduction to Database
 File-Based Approach
 Each program defines and manages its own data
 Limitation
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Separation and isolation of data
Duplication of data
Data dependence
Incompatibility of files
Fixed queries/proliferation of application program
 Database Approach
 A shared collection of logically related data, designed to meet the
information needs of an organization
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Dept. of Multimedia, KEUKDONG College
Introduction to Database
 Database Management System(DBMS)
 A software system that enables users to define, create and maintain
the database and provides controlled access to database
 DDL
 DML : procedural, non-procedural
 Control : security, integrity, concurrency control,
» recovery control, user-accessible catalog
 Components of the DBMS Environment
 Hardware - Software - Data - Procedures - People
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Dept. of Multimedia, KEUKDONG College
Introduction to Database
 Advantages of DBMS
- Control of data redundancy - Economy of scale
- Data consistency
- Balance of conflicting requirements
- More information from the same amount of data
- Sharing of data
- Improved data accessibility and
responsiveness
- Improved data integrity
- Increased productivity
- Improved security
- Improved maintenance through data
independence
- Enforcement of standards
- Increased concurrency
- Improved backup and recovery services
 Disadvantages of DBMS
- Complexity, Size, Cost of DBMSs, Additional H/W costs
- Cost of conversion, Performance, Higher impact of a failure
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Dept. of Multimedia, KEUKDONG College
Introduction to Database
 Three-Level Database Architecture
 External Level
 The users’ view of the database
 Conceptual Level
 The community view of the database
 Internal Level
 The physical representation of the database on the computer
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Dept. of Multimedia, KEUKDONG College
Introduction to Database
 Functions of a DBMS
1. Data storage, retrieval, and update
2. A user-accessible catalog
3. Transaction support
4. Concurrency control services
5. Recovery services
6. Authorization services
7. Support for data communication
8. Integrity services
9. Services to promote data independence
10. Utility services
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Dept. of Multimedia, KEUKDONG College
Introduction to Database
History of DBMS
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1960s - Apollo moon-landing project, GUAM
mid 1960s - IMS by IBM (hierarchical DBMS)
mid 1960s - IDS by GE (network DBMS)
1965 - CODASYL(Conference on Data SYStems Language)
1967 -DBTG(Data Base Task Group)
1970 - E.F.Codd of the IBM Research Lab.
Late 1970s - System R project at IBM
1980s - commercial relational DBMS(DB2, Oracle, Informix..)
Now - OODBMS, ORDBMS
Dept. of Multimedia, KEUKDONG College
Introduction to Database
 Terminology
 Relation : a relation is a table with columns and rows
 Attribute : an attribute is a named column of a relation
 Domain : a domain is the set of allowable values for one or more
attributes
 Tuple : a tuple is a row of a relation
 Degree : the degree of a relation is the number of attributes it
constrains
 Cardinality : the cardinality of a relation is the number of tuples it
contains
 Relational database : a collection of normalized relation
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Dept. of Multimedia, KEUKDONG College
Introduction to Database
 Properties of Relations
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The relation has a name that is distinct from all other relation names
Each cell of the relation contains exactly on atomic value
Each attribute has a distinct name
The values of an attribute are all from the same domain
The order of attributes has no significance
Each tuple is distinct; there are no duplicate tuples
The order of tuples has no significance, theoretically
Dept. of Multimedia, KEUKDONG College
Introduction to Database
Entity-Relationship Modeling
 Concepts of the E-R Modeling
 Entity Types
 An object or concept that is identified by the enterprise as
having an independent existence
 Attributes
 A property of an entity or a relationship type
 Relationship Types
 A meaningful association among entity types
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Dept. of Multimedia, KEUKDONG College
Introduction to Database
Database Language
 SQL
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1974 - SEQUEL by D.Chamberlin (IBM)
1975 - SQUARE by Boyce (System R project)
1976 - SEQUEL/2 (SQL) by Chamberlin and Boyce)
late 1970 - SQL(Oracle), QUEL(Ingres)
1982 - Relational Database Language(RDL) : ANSI
1987 - ISO standard
1989 - Integrity Enhancement Feature (ISO)
1992 - SQL2(SQL92) : ISO
Dept. of Multimedia, KEUKDONG College
Introduction to Database
 DML
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SELECT
INSERT
UPDATE
DELETE
 DDL
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CREATE(DROP) SCHEMA
CREATE(ALTER, DROP) DOMAIN
CREATE(ALTER, DROP) TABLE
CREATE(DROP) VIEW
CREATE(DROP) INDEX
Dept. of Multimedia, KEUKDONG College
Introduction to Database
 Advanced SQL
 View
 Integrity Enhancement Feature
 Primary key
 Unique
 Foreign key
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Access Control
Embedded SQL
Host Language Variables
Application Programming Interface
Dynamic SQL
Dept. of Multimedia, KEUKDONG College