Qestion:

Reflect upon the desirable characteristics of a primary key that were presented in this weeks lecture. Choose one characteristic and discuss why you believe it would be undesirable if this were not a characteristic of a primary key.

The week lecture:

The primary key of a table is how we identify data in the table, so it is especially important to choose a proper primary key. There are several characteristics that are considered desirable in a primary key.

First, a primary key should be unique. It can never have a duplicate. This should be obvious since we are using the keys for identification of specific information. This is also one reason why we typically dont consider names good choices for primary keys, since two or more people can have the same name.

Next, a primary key should be stable, meaning it should never change. This is another reason why names are not considered good primary keys. Names do change: marriage, divorce, and adoption are three circumstances that readily spring to mind that might cause a name change.

Additionally a primary key should be minimal. It should use the fewest number of attributes possible. Also, it should be accessible, meaning its available as soon as the data is created.

Furthermore, a primary key should be factless. It should contain no information that has meaning. Meeting this characteristic helps ensure the key is security-compliant, because if the key is factless it will not contain any personally identifiable information suchSocial Security Numbers.

When taken together, these characteristics point to the desirability of a numeric key for the primary key. Because of this we often use a surrogate key for the primary key. We can generate a numeric surrogate key with each record, which results in the primary key meeting all the desirability characteristics. While there are occasional instances where a surrogate key is not the best choice, for the purposes of this class it will be a good idea to get into the habit of using a surrogate key for the primary key.

PLEASE ANSWER WITH YOUR OWN WORDS

Thanks