engineering computer science MCQ #879

engineering computer science MCQ #879

1. Question 1

   Q1. What is the difference between a primary key and a unique key?

   • A) A primary key can be null, while a unique key cannot be null
   • B) A primary key is used for indexing, while a unique key is not
   • C) A primary key uniquely identifies a record, while a unique key ensures uniqueness but can be null
   • D) A primary key is used for data encryption, while a unique key is not

   Answer: A primary key uniquely identifies a record, while a unique key ensures uniqueness but can be null

   Explanation: A primary key uniquely identifies a record and cannot be null, while a unique key ensures uniqueness but can be null.