ERD To Data Model Transformation

The Entity Relationship Diagram (ERD) to Data Model transformation converts an ERD logical model to a data model targeted at the default database type, ready for  generating DDL statements to run in one of the system-supported database products. Before doing the transformation, you define the common data type for each attribute and select a database type as the default database. You can then automatically generate the data modeling diagram.

The transformation uses and demonstrates support in the intermediary language for a number of database-specific concepts.

Concepts

Concept

Definition

See also

Table

Mapped one-to-one onto Class elements.

 

 

Column

Mapped one-to-one onto attributes.

 

 

Primary Key

Lists all the columns involved so that they exist in the Class, and creates a Primary Key Method for them.

 

 

Foreign Key

A special sort of connector, in which the Source and Target sections list all of the columns involved so that:

The columns exist
A matching Primary Key exists in the destination Class, and
The transformation creates the appropriate Foreign Key
 

Transform Foreign Keys

 

Generalization

ERD technology can handle Generalization, as shown. Note that the copy-down inheritance is currently supported with two levels only.

Example

The ERD elements

ERDGen

 

After transformation, become the Data Model elements

erdgentrans

Notes

Sometimes you might go back to the ERD, make some changes and then need to do another transformation; in this case, to achieve better results, always delete the previous transformation package before doing the next transformation
 

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