Data Moddeling

1. DA TA MODELLING INTRODUCTION

2. THANK YOU

3. WHAT IS DATA MODELL ING

4. WHY DO WE NEED TO CREATE DATA MODELS? TO AID IN THE DEVELOPMENT OF A SOUND DATABASE DESIGN THAT DOES NOT ALLOW ANOMALIES OR INCONSISTENCIES GOAL: TO CREATE DATABASE TABLES THAT DO NOT CONTAIN DUPLICATE DATA VALUES THAT CAN BECOME INCONSISTENT

5. YPES OF DATA MODELS ENTITY-RELATIONSHIP (E-R) MODEL ONLY ADDRESSES DATA AND RELATIONSHIPS CLASSIC, SIMPLEST BEST FOR DERIVING A SOUND TABLE DESIGN MANY EXTENSIONS/VARIATIONS EXIST BASIS FOR MOST OTHER MODELING APPROACHES UML (UNIFIED MODELING LANGUAGE) CLASS MODELS GOES BEYOND DATA, ALSO MODELS BEHAVIORS

6. CREATING AN ENTITY-RELATIONSHIP MODEL IDENTIFY ENTITIES IDENTIFY ENTITY ATTRIBUTES AND PRIMARY KEYS SPECIFY RELATIONSHIPS

7. DATA ENTITIES ENTITY A "THING" ABOUT WHICH YOU WANT TO STORE DATA IN AN APPLICATION MULTIPLE EXAMPLES (INSTANCES) OF THE ENTITY MUST EXIST GOAL: STORE DATA ABOUT EACH ENTITY IN A SEPARATE TABLE DO NOT STORE DUPLICATE DATA IN MULTIPLE TABLES OR RECORDS EXAMPLES: CUSTOMER, PRODUCT www.yourwebsite.com

8. DATA ENTITY INSTANCES ENTITY INSTANCE A SPECIFIC OCCURRENCE (DATA VALUE) OF AN ENTITY AN ENTITY MUST HAVE MULTIPLE ENTITY INSTANCES OR IT IS NOT REALLY AN ENTITY! EXAMPLES: BOBBY BON BONS, CELESTIAL CASHEW CRUNCH

9. THANK YOU