Convert ER to Relational Data Models

four steps in database design

(1) developing ER diagram (conceptual), mapping the ER diagram into relational model (logical), (3) normalizing (optimized), (4) instantiating the database (real)

weak entity format

(1) include all simple attributes, (2) flatten composite attributes (NOTE - PK will be finalized after relationship is mapped)

strong entity type format

(1) include all simple attributes, (2) flatten composite attributes, (3) underline PK

example of client address in relational schema (assume PK: clientNo)

Client (clientNo, addressNo, streetName, city, zip)

if unary one-to-many relationship exists, make a copy of the _________ and rename it as the _________

PK, FK

one-to-many relationship (PK)

add copy of parent PK into child relation (as a FK)

four steps in database design at a high-level

conceptual, logical, optimized, real

do you map entities or relationships first?

entities

one-to-many relationship (parent and child)

entity on one (1) side = parent, entity on many (*) side = child

true/false: every aspect of an ER diagram can be mapped into a relational schema

true (though simplification is sometimes required)

two challenges of creating relational data models

where to put FK, identify parent relation