1. An Introduction to database system
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2. Basic Definitions
Data: Meaningful facts, text, graphics, images, sound, video segments.
Database: An organized collection of logically related data.
Information: Data processed to be useful in decision making.
Metadata: Data that describes data.
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3. What is a DataBase system? (DB)
It is a logically coherent collection of data with inherent meaning.
It represents a miniworld, and should represent the state of that world accurately.
It is managed by a database management system (DBMS).
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4. What is a DataBase Management System? (DBMS)
A (large) piece of software which provides an interface between the user or application program and the stored data.
A DBMS is developed according to a particular data model.
Some example DBMSs are:
IMS, DB2, Oracle, Sybase, Informix, SQL Server, Access, FoxPro, O2.
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5. The functionality of DBMS
Manages very large amounts of data.
Supports efficient access to very large amounts of data.
Supports concurrent access to very large amounts of data.
Supports secure, atomic access to very large amounts of data.
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6. Several basic concepts
Data models
A data model is a way of representing (part of) the world.
The principle current data model are:
Hierarchical
Network
Relational
Object-oriented
E-R
Semantic
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7. Several basic concepts
Database design
Design goals
Minimize redundancy in order to eliminate the modification anomalies in database.
Represent the situation accurately
Design Stages
Conceptual (product independent)
Logical (product specific)
Physical / Implementation (product specific)
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8. Database Development Activities
The stages
focused
in COP4540
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9. Conceptual Database Modeling
Determine user requirements.
Determine business rules.
Build conceptual data model
outcome is an entity-relationship diagram or similar communication tool.
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10. Logical Database Design
Select logical database model.
Map Entity-Relationship Diagrams
Normalize data structures.
Specify business rules.
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11. Physical Database Design
Select DBMS
Select storage devices
Determine access methods
Design files and indexes
Determine database distribution
Specify update strategies
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12. Several basic concepts
Schema
Logical structure of the data defined by using data definition language (DDL).
Queries
A “query” is a database lingo for a question about the data.
A “query” is composed by using query language (QL)
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13. The architecture of database system
Users / Programmers
Application Programs / Queries
1. Software to process
queries/programs
2. Software to access stored
data
Database Management System
Stored data
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14. Components of the Database Environment
CASE Tools
Repository
Database Management System (DBMS)
Database
Application Programs
User Interface
Database Administrators (DBA)
System Developers
End Users
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15. Evolution of Database Systems
Hierarchical and Network (Legacy): Data are modeled as linked records.
Relational: Data are modeled as related tables.
Object-oriented: Data are organized as linked objects.
Object-relational: Integration of relational and object-oriented features.
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16. RDBMS and SQL RDBMS is a DBMS on the basis of relational model.
It is the most popular type of the DBMS.
The data is organized as tables called relations
Two famous systems:
System R at IBM & Ingres at UC Berkeley
SQL (Structured Query Language)
the most important query language based on relational model.
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17. RDBMS and SQL SELECT balance Result: FROM Accounts 2846.92
WHERE accountNo = 67890
Result:
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18. Disadvantages of File Processing Systems
Data Dependence
Data Redundancy (Duplication of data)
Limited Data Sharing
Lengthy Development Times
Excessive Program Maintenance
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19. Advantages of Database Approach
Program-Data Independence: No need to rewrite programs when data is modified
Minimal Data Redundancy
Improved Data Consistency
Improved Data Sharing
Increased Application Development Productivity.
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20. Advantages of Database Approach
Enforcement of Standards
Improved Data Quality (Constraints)
Better Data Accessibility/Responsiveness
Reduced Program Maintenance
Security, Backup/Recovery, Concurrency
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21. Costs and Risks of the Database Approach
New, Specialized Personnel
Installation Management Cost and Complexity
Conversion Costs
Organizational Conflict
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