The rules are the following:
a conceptual entity becomes a logical entity; the key of the conceptual entity becomes the key of the logical entity;
a conceptual property is translated into a logical property.
Important note: When generating the Logical Data Model, the names of the logical properties (guide word, associated field name, short name, name of the property in case of redundancy) are automatically built by transformation programs known as naming convention programs.
Note: In a "X,N-Y,1" relationship (X and Y may take the values 0 or 1), the SOURCE entity is the entity holding the "X,N" cardinality, and the TARGET entity is the entity holding the "Y,1" cardinality.
Role of the entities in a relationship of the "X,N-Y,1" type
Important note: Case of an existing Logical Data Model: the generation of the Logical Data Model complies with the modifications brought to an existing Logical Data Model.
Also, the generation of the Logical Data Model only applies to data modified at the Conceptual level.
A request for generating the whole Logical Data Model can be made by selecting all the application areas in the Generate LDM dialog box, and first by clicking the Modify button, then the Generate button.
The program for transforming conceptual names into logical names can be customized.
The transformation rules of a Conceptual Data Model's object names into a Logical Data Model are the following:
Name of a physical file: first eight characters of the logical entity name.
Name of a logical file, depending on the origin of the file:
- if the file is coming from the generation of the logical entity: first seven characters of the logical entity name, suffixed by the character "L";
- if the file is coming from the generation of an access: eight first characters of the access name.
Name of a format: seven first characters of the logical entity name, suffixed by the character "F".