Question

The primary key is chosen from ________.

• A. The most complex candidate key available.
• B. All available candidate keys for a table
• C. The simplest candidate key available.
• D. Any attribute within the table

Answer 1

The Correct Option is C

The primary key in a database is essential for uniquely identifying each record within a table. When selecting a primary key, there are often multiple candidate keys to choose from. A candidate key is a set of attributes that can uniquely identify a tuple in a table. The primary key is typically chosen from these candidate keys based on simplicity and efficiency. 

From the provided options, the correct choice is: The simplest candidate key available. This means that when deciding on a primary key among several candidate keys, preference is usually given to the key that is simplest in terms of structure and requires the minimum number of attributes. Simplicity in a primary key improves database performance and reduces complexity in data management.

Answer 2

The correct answer is (3) The simplest candidate key available. 

Candidate Key: A candidate key is a column or set of columns that can uniquely identify each row in a table. 

Primary Key: A primary key is a specific candidate key chosen as the main identifier for the table. 

The selection criteria are generally based on: 

• Uniqueness: Must uniquely identify each record. 
• Minimal: Should be the smallest set of attributes that still ensures uniqueness. 
• Simplicity: Easy to understand and work with. 
• Stability: Should rarely or never change its value. 

Therefore, the simplest candidate key that fulfills the requirement of uniqueness is preferred as the primary key for ease of use, performance, and reduced storage space.