Database Design

Question 1

What are the 4 stages of DB design? ECLP

Answer 1

1. External Modelling
2. Conceptual Modelling
3. Logical Modelling
4. Physical Modelling

Question 2

First step?

Answer 2

1. External Modeling
   Potential users define their own subset of the real world, that is,
   what is relevant for their needs
   ◦ each subset or view typically describes the part of the database in which a
   particular user group is interested, and hides the rest of the database
   ◦ commonly, we have as many external models as we have different purposes
   ◦ usually consist of narration of requirements obtained from interview process
   ◦ emphasis on functional capabilities and data requirements
   ◦ Identify the spatial information products that will be produced by the
   organization

Question 3

Second step?

Answer 3

2. Conceptual Modelling
   Model different user views of the data
   Describe and defines all entity types included in the database
   Identify the key thematic layers to be represented in the database
   Identify how entities will be represented as database objects
   ◦ Scale specific selection of spatial objects - points, lines, areas, rasters
   Group representations into datasets
   ◦ Feature datasets, feature classes, relationships, domains

Question 4

third step?

Answer 4

3. Logical Modeling
   Determine the structure of the tabular database and the behaviour of the descriptive attributes
   ◦ Identify: fields, valid values and ranges, relationships
   Define the spatial properties of the database
   ◦ Networks – of connected features
   ◦ Topology rules
   Prepare a database design

Question 5

fourth step?

Answer 5

4. Physical Modeling
   Implement, prototype, review, refine the design
   ◦ Design will likely have to be tuned once the system is implemented
   Develop and test applications designed to work with the database
   Assess data products produced
   Design work flows for building and maintaining each layer
   Document the design