TABLE OF CONTENTS Forward engineering is the process of transforming higher level models to lower level models. Figure 7-1 displays an overview of this process, starting at the conceptual level (ORM), mapping to the logical level (ER or relational), and then generating the physical database model. The first stage, mapping ORM models to logical database models, is called the build process and is the main focus of this chapter.
The second stage, transforming a logical database model to a physical database schema, is called the generate process. It is usually best to first generate the data definition language (DDL) script containing the SQL statements for creating the relational schema, so you can check it over. Once you are happy with the DDL script, you can execute it in your chosen DBMS to create the actual database schema. With some DBMSs, you may also generate the database schema directly if connected to the DBMS.
If you later make changes to the logical database model, you can propagate those changes to the existing database by using the update process. The generate and update processes are covered in detail in later chapters and are not discussed further here.
Chapter 3 included a simple example to illustrate the basic process of building a single logical model from a single ORM model. As illustrated in Figure 7-1, it is also possible to build a logical model...
