Multiple choice technology databases

What is true about NOT NULL constraint? Choose all that apply

  1. Must be defined as a part of column definition

  2. It's NOT necessary to define it as a part of column definition

  3. Can be applied to the column which may hold UNKNOWN data

  4. Can NOT be applied to the column which may hold UNKNOWN data
Reveal answer Fill a bubble to check yourself
A,D Correct answer
Explanation

NOT NULL must be defined as part of the column specification (inline or table-level but with column context). Since NOT NULL prohibits NULL values, it cannot be applied to columns that legitimately hold unknown/missing data - that's the purpose of allowing NULLs.

Keep practicing — related questions