Multiple choice

Which of the following is true?

i. A primary key by default checks for not null and uniqueness conditions. ii. A primary key by default checks only for uniqueness. iii. A primary key can be a composite key. iv. A primary key can never be a composite key.

  1. i. and iv. are true

  2. i. and iii. are true

  3. ii. and iv. are true

  4. ii. and iii. are true
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

This answer is correct. A primary key by default checks for both not null and the uniqueness conditions. Primary key will verify whether the value inside the column is null or not, and also unique from the other values or not. A primary key can also be a composite key. It can have one or more columns as a primary key.

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