Chapter 7 how to model and design a database

Data Modelling

= the art of database design

Find out

which facts : things (entiy). keep what (attribute), model what might happen, how the facts link (relationship)

Not

process, data flow, experimental design

Make a database metadata

identify the facts to be stored in the database client and analysit

Building Blocks

entity attribute relationship identifiers (+ and frim’boss 是什么？) Q

Aim 1 a well formed data model

Construction rules obeyed No ambiguity

Aim 2 a high fidelity image

faithfully describes the world relationships data model is complete, understandable and accurate make sense

7 habits of highly effective data modellers

Integrate

more than one capital same name cities label these relationship

Normalization

Bottom-up Grouping the attributes in tables so that Every non-PK attributes depends on – the PK, – the whole PK (if multi-attribute), – and nothing but the PK

Generalize

man and woman can be generelized as person child /// single marriage

Cardinality and Modelity

cardinality range of instances modelity participating instances