spatial DB design tools and templates. oct 4

Question 1

List the stages in DB design

Answer 1

Conceptual: user view> objects and relationships > geographic representation
Logical: geographic database types > geographic database structure
Physical model: database schema

Question 2

list 3 conceptual design methods of top-down design

Answer 2

• data flow diagrams
• entity-relationship diagrams
• unified modelling language

Question 3

list and explain the 5 components of ERDs

Answer 3

• entities (a real world element, i.e. river)
• weak entities (a subset of entities. i.e. turbidity, velocity of river)
• attributes (single vs multi-valued); identifier
• relationships (aggregation, generalisation & specialization, association, cardinality; participation can be mandatory or optional)
• integrity constraints (normalization)

Question 4

define data normalization

Answer 4

decomposing complex data structure into simpler and stable tables that can be related

Question 5

How do we normalize?

Answer 5

1st, 2nd, or 3rd Normal Form

Question 6

what are some best practices?

Answer 6

• user-centred design approach (prototyping. but sometimes users dont know what they need)
• using both GIS-specif approaches an RDBMS design (i.e. applying Tomlinson’s to GIS)