The Data Schema Diagram
After the relational model has been created, the information needed to write SQL is available. If this information was documented in Oracle’s Designer6i tool, a data schema diagram can be developed, which is the document of choice to determine the information needed to write your SQL. If you do not have Designer6i available, you can create a document that I call a table relationship diagram. I will discuss this in the next section.
Figure 1.8 illustrates a database relationship diagram based on the entity relationship diagram depicted in Figure 1.6. At first glance, the two documents look similar, especially because the entities shown in Figure 1.6 have been normalized. However, there are some important differences:
Get Oracle SQL and PL/SQL Handbook: A Guide for Data Administrators, Developers, and Business Analysts now with the O’Reilly learning platform.
O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.
