The primary key is selected from the

Answer- A. Candidate keys

The primary key is selected from the candidate keys.

Solution

The answer to the above question is that the primary key is selected from the candidate keys. A primary key is an attribute or set of attributes, that can be used to distinguish one row of data from another in a table from a variety of candidate keys, at least one of which has a non-null field value. The candidate keys whose attribute values are not null are chosen as the primary key.

Foreign key references are typically the primary key of the same table or another table. But it can also refer to other columns. The attribute in one of the tables is designated as the primary key whenever the same type of attribute is present in two different tables. On the other, it is made from a foreign key so that the values in both become consistent.

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