Database Reference
In-Depth Information
Figure 10.50. Data relationships between the PARTS and PART COMPONENTS
tables
Now, use the techniques you've just learned to establish all of the relationships you've
identified among the tables in the database. Make absolutely certain you create a diagram
foreachrelationship—you'regoingtoaddnewinformationtothesediagramsasthedesign
process unfolds further.
Reviewing the Structure of Each Table
Review all of the table structures after you've established the relationships between tables.
Remember that you made modifications to the existing table structures and created several
new table structures as you established the relationships; therefore, you want to make cer-
tain that each table conforms to the Elements of the Ideal Table.
Elements of the Ideal Table
• It represents a single subject, which can be an object or event.
• It has a primary key.
• It does not contain multipart or multivalued fields.
• It does not contain calculated fields.
• It does not contain unnecessary duplicate fields.
• It contains only an absolute minimum amount of redundant data.
When you determine that a table does not comply with the Elements of the Ideal Table ,
identify the problem and make the necessary modifications. Then, take the table through
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