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new dependency diagrams. For each new table created, specify its
normal form (1NF, 2NF, 3NF).
Figure 2- solution 2
Discussion: To achieve 2NF, we must remove partial dependencies.
This is done by decomposing into three tables, and three dependency
diagrams at this stage. Notice that the Transitive relationship has not
yet been addressed.
3. Using the answer to exercise 3, remove all transitive
dependencies, and draw the new dependency diagrams. For each new
or revised table, specify its normal form.
Figure 3 – Solution 3
Discussion: The transitive relationship has been removed by creating
the Publishers table, in which PubName is fully dependent upon
PubCode. Pubcode also persists as a dependent attribute and Foreign
Key in Books. All tables are now in 3NF, and have been given
meaningful names reflecting the entities they represent. LINEITEMS
represents the collection of line items for all invoices. Invoices
represents the collection of Invoices for all customer orders. Books
makes up the list of all books available for sale (whether they have
ever been ordered or not). Each book has a publisher, and the
publisher code and Name reside in the Publishers table.
4. Draw the ERD for exercise 3, using Crow‘s Foot notation.
End of Sample Exercise.
Student Exercise
The student exercise for this lab is similar to the sample exercise
presented above.