Logical Diagrams

A logical data diagram provides a graphical view of the structure of an information system, and helps you analyze the structure of your data system through entities and relationships, in which primary identifiers migrate along one-to-many relationships to become foreign identifiers, and many-to-many relationships can be replaced by intermediate entities.

To create a logical diagram in an existing LDM, right-click the model in the Browser and select  New  Logical Diagram . To create a new model, select  File  New Model , choose Logical Data Model as the model type and Logical Diagram as the first diagram, and then click OK.

The following logical diagram represent the same system as that in our CDM example (see Conceptual Diagrams), but primary identifiers have migrated along one-to-many relationships to become foreign identifiers, and many-to-many relationships are replaced with an intermediary entity linked with one-to-many relationships to the extremities.

The following objects can be created in a conceptual diagram:

Tool	Description
	Entity - A person, place, thing, or concept that is of interest to the enterprise. See Entities (CDM/LDM).
[none]	Entity Attribute - An elementary piece of information attached to an entity. See Attributes (CDM/LDM).
[none]	Domain - A set of values for which a data item is valid. See Domains (CDM/LDM/PDM).
[none]	Identifier - One or many entity attributes, whose values uniquely identify each occurrence of the entity. See Identifiers (CDM/LDM).
	One-Many, One-Many Dependent, Many-Many Relationship - A connection between entities (ER modeling methodology). See Relationships (CDM/LDM).
	Inheritance - A relationship that defines an entity as a special case of a more general entity. See Inheritances (CDM/LDM).