August 2002
Intermediate to advanced
528 pages
10h 12m
English
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: