database management cop4540, scs, fiu

Database ManagementCOP4540, SCS, FIU

An Introduction to database system


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.


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).


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.


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.


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 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 Development Activities

Enterprise ModelingConceptual Data Modeling

Logical DB Design

Physical DB DesignDB Implementation

DB Maintenance

} The stages focused in COP4540


Conceptual Database Modeling

• Determine user requirements.

• Determine business rules.

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

similar communication tool.


Logical Database Design

• Select logical database model.

• Map Entity-Relationship Diagrams

• Normalize data structures.

• Specify business rules.


Physical Database Design

• Select DBMS

• Select storage devices

• Determine access methods

• Design files and indexes

• Determine database distribution

• Specify update strategies



• 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)


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


Components of the Database Environment

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


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.


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.


RDBMS and SQL

accountNo balance type

12345 1000.00 savings

67890 2846.92 checking

Accounts

SELECT balanceFROM AccountsWHERE accountNo = 67890

Result: 2846.92


Disadvantages of File Processing Systems

• Data Dependence

• Data Redundancy (Duplication of data)

• Limited Data Sharing

• Lengthy Development Times

• Excessive Program Maintenance


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.


Advantages of Database Approach

• Enforcement of Standards

• Improved Data Quality (Constraints)

• Better Data Accessibility/Responsiveness

• Reduced Program Maintenance

• Security, Backup/Recovery, Concurrency


Costs and Risks of the Database Approach

• New, Specialized Personnel

• Installation Management Cost and Complexity

• Conversion Costs

• Organizational Conflict

database management cop4540, scs, fiu

Documents

stored data

related data

data structures

large amounts of data

particular data model

basic definitions data

coherent collection

database distribution