Database Design Principles - Access Database Design and Programming - page 41

{ISBN,Title,AuID}

and:

{AuID,AuName}

we have normalized the database into first normal form.

Here is another example involving the higher normal forms. Recall from an earlier
example that the table scheme {City,StreetName,ZipCode}, with dependencies:

{City,StreetName} {ZipCode}

and:

{ZipCode} {City}

is in third normal form. However, Table 4-5 shows that there is still some redundancy in
the table scheme. The table scheme is not in BCNF. In fact, this was the example we used
to motivate our definition of BCNF. (The example violates BCNF.)

Ta b le 4-5. A table with redundant data

City StreetName ZipCode

L os Angeles Hollywood Blvd 95000

Vine St 95000

However, we can split this table scheme into two schemes:

{ZipCode,City}

and:

{ZipCode,StreetName}

In this case, Table 4-5 gets split into two tables, Tables Table 4-6 and Table 4-7, and the
redundancy is gone!

Table 4-6. First table derive d from Table 4-5 to eliminate redundancy
ZipCode City

95000 Los Angeles

Table 4-7. Second tabl e derived from Table 4-5 to eliminate redundancy
ZipCode

StreetName

9 5000 Hollywood Blvd

95000 Vine St