Summary of Logical and Physical Model Components

The following table summarizes the relationship between objects in a logical and a physical model:

Logical Model

Physical Model

Entity

Table

Dependent entity

Foreign Key is part of the child table's Primary Key

Independent entity

Parent table or, if it is a child table, Foreign Key is NOT part of the child table's Primary Key

Attribute

Column

Logical datatype (text, number, datetime, blob)

Physical datatype (valid example varies depending on the target server selected)

Domain (logical)

Domain (physical)

Primary key

Primary key, Primary Key Index

Foreign key

Foreign key, Foreign Key Index

Alternate key (AK)

Alternate Key Index-a unique, non-primary index

Inversion entry (IE)

Inversion entry Index-a non-unique index created to search table information by a non-unique value, such as customer last name.

Key group

Index

Business rule

Trigger or stored procedure

Validation rule

Constraint

Relationship

Relationship implemented using Foreign Keys

Identifying relationship

Foreign Key is part of the child table's Primary Key (above the line)

Non-identifying relationship

Foreign Key is NOT part of the child table's Primary Key (below the line)

Subtype relationship

Denormalized tables

Many-to-many relationship

Associative table

Referential Integrity relationship (Cascade, Restrict, Set Null, Set Default)

INSERT, UPDATE, and DELETE Triggers

Cardinality relationship

INSERT, UPDATE, and DELETE Triggers

N/A

View or view relationship

N/A

Prescript or postscript

Referential integrity is a part of the logical model, since the decision about how to maintain a relationship is a business decision. Referential integrity is also a physical model component, since triggers or declarative statements appear in the schema. Referential integrity is supported as a part of both the logical and physical models.