Mapping ORM Models to Logical Database Models

This chapter gives an overview of forward engineering process, the process of transforming higher-level models to lower-level models that starts at the conceptual level object-role modeling (ORM) for mapping to the logical level (ER or relational) and generating the physical database model. The first stage of mapping ORM models to logical database models is called the build process. The second stage of transforming a logical database model to a physical database schema is called the generate process. It is best to first generate the data definition language (DDL) script containing the structured query language (SQL) statements for creating the relational schema. With some DBMSs, it can also generate the database schema directly if connected to the DBMS. When a logical database model is built from one or more ORM source models, the tool creates a project to house relevant documents. In addition to the logical database model, the project may contain nonsource documents, such as a text file that might be added to the project for further documentation. To transform a set of one or more ORM models to a logical database model, the ORM model(s) should be added first to a database model project for the purpose of project building.