Primary key: In relational databases, a primary key is a key that is used for identifying and defining the characteristics uniquely of each row. A primary key may have a single attribute or a multiple attributes. Let us consider the “Student” table that consists of “Student_ID”, “First_Name”, “Last_Name”, and “Course_ID” as attributes. Student_ID act as the primary key. Candidate key: Candidate key is an attribute or set of attributes from which a primary key can be selected. It helps to identify the data uniquely from the table or relation without referring any other data. One or more candidate keys can be present in a table or relation, but only one key is referred to as the primary key. Candidate key must satisfy the subset of the properties of relation.

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Chapter 2, Problem 2.13RQ

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Primary key:

In relational databases, a primary key is a key that is used for identifying and defining the characteristics uniquely of each row.

A primary key may have a single attribute or a multiple attributes.

Let us consider the “Student” table that consists of “Student_ID”, “First_Name”, “Last_Name”, and “Course_ID” as attributes.

Student_ID act as the primary key.

Candidate key:

Candidate key is an attribute or set of attributes from which a primary key can be selected.

It helps to identify the data uniquely from the table or relation without referring any other data.

One or more candidate keys can be present in a table or relation, but only one key is referred to as the primary key.

Candidate key must satisfy the subset of the properties of relation.

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