database management cop4540, scs, fiu

Database ManagementCOP4540, SCS, FIU

An Introduction to database system

Database ManagementCOP4540, SCS, FIU

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.

Database ManagementCOP4540, SCS, FIU

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).

Database ManagementCOP4540, SCS, FIU

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.

Database ManagementCOP4540, SCS, FIU

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.

Database ManagementCOP4540, SCS, FIU

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

Database ManagementCOP4540, SCS, FIU

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)

Database ManagementCOP4540, SCS, FIU

Database Development Activities

Enterprise ModelingConceptual Data Modeling

Logical DB Design

Physical DB DesignDB Implementation

DB Maintenance

} The stages focused in COP4540

Database ManagementCOP4540, SCS, FIU

Conceptual Database Modeling

• Determine user requirements.

• Determine business rules.

• Build conceptual data model– outcome is an entity-relationship diagram or

similar communication tool.

Database ManagementCOP4540, SCS, FIU

Logical Database Design

• Select logical database model.

• Map Entity-Relationship Diagrams

• Normalize data structures.

• Specify business rules.

Database ManagementCOP4540, SCS, FIU

Physical Database Design

• Select DBMS

• Select storage devices

• Determine access methods

• Design files and indexes

• Determine database distribution

• Specify update strategies

Database ManagementCOP4540, SCS, FIU

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)

Database ManagementCOP4540, SCS, FIU

The architecture of database system

Users / Programmers

Application Programs / Queries

Database Management System

1. Software to process queries/programs

2. Software to access stored data

Stored data

Database ManagementCOP4540, SCS, FIU

Components of the Database Environment

• CASE Tools• Repository• Database Management System (DBMS)• Database• Application Programs• User Interface• Database Administrators (DBA)• System Developers• End Users

Database ManagementCOP4540, SCS, FIU

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.

Database ManagementCOP4540, SCS, FIU

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.

Database ManagementCOP4540, SCS, FIU

RDBMS and SQL

accountNo balance type

12345 1000.00 savings

67890 2846.92 checking

Accounts

SELECT balanceFROM AccountsWHERE accountNo = 67890

Result: 2846.92

Database ManagementCOP4540, SCS, FIU

Disadvantages of File Processing Systems

• Data Dependence

• Data Redundancy (Duplication of data)

• Limited Data Sharing

• Lengthy Development Times

• Excessive Program Maintenance

Database ManagementCOP4540, SCS, FIU

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.

Database ManagementCOP4540, SCS, FIU

Advantages of Database Approach

• Enforcement of Standards

• Improved Data Quality (Constraints)

• Better Data Accessibility/Responsiveness

• Reduced Program Maintenance

• Security, Backup/Recovery, Concurrency

Database ManagementCOP4540, SCS, FIU

Costs and Risks of the Database Approach

• New, Specialized Personnel

• Installation Management Cost and Complexity

• Conversion Costs

• Organizational Conflict