What are the main criteria to consider when choosing and defining a primary key in a database table?

When choosing a primary key in a database table, the following criteria should be considered:

• Uniqueness: The key value must uniquely identify each record.
• Immutability: The primary key value should not change over time.
• Minimal size: The key should be compact to optimize indexes and performance.
• Simplicity: It is better to use a simple data type (e.g., numeric or UUID).
• No NULLs: The primary key cannot contain NULL.

For example, an auto-incrementing numeric field or UUID is often used as a primary key.