According to the "preferably single-attribute" characteristic of a primary key, the primary key:
a. must be able to guarantee unique attribute values.
b. should have the minimum number of attributes possible.
c. should have embedded semantic meaning associated with each attribute.
d. must be composed of attributes that are free from security risks or violations.

There are different types of keys used in it. Example, primary key, secondary key, natural key, foreign key. Each key has it's own value.

The primary key is the "single-attribute" key. These are the keys which have a main function of uniqueness. The primary key is know for it's single unique attribute. Its main function is uniquely identify the attributes in a given table. The primary key along with the foreign key also implement the relations between the entities.

The main characteristics of primary key are:

Uniqueness : It gives a unique value.
Non-intelligent : it should not have embedded semantic meaning with each attribute.
No change over time: It should be permanent and unchangeable
Single attribute : A primary key should have minimum number of attributes possible. Single attribute primary key helps to implement foreign key easily.
Preferably numeric : It can be better managed if the unique values are numeric in nature.
Security-compliant : Any selected primary key must not have any attribute that may be considered as a security risk or violation. It must be composed of attributes that are free from security risks or violation.

Thus, from this we can conclude that primary key must be to guarantee unique attribute values, should have the minimum number of attributes and must be composed of attributes that are free from security risks or violation.

To know more about primary key, refer: https://brainly.com/question/13188566

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