Chapter 6 Normalization

What’s wrong with it
Given the following table
ID Name Address Hobby
1111 John Doe 123 Main St. Stamps
1111 John Doe 123 Main St. Coins
2222 Mary Doe 7 Lake Dr. Acting
If John Doe moves to 1 Russell Street, we have
to change the address information in both tuples
for John. Imagine what happens if John
has 123 hobbies.
We either have to update this information 123
times, and if we miss even one, the information
will no longer consistent.(Update abnormally)
A reason for this abnormally is that the address
information is redundantly kept: we have to
repeat it for every combination of key value.
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