Multiple choice technology databases

Which constraint can be defined only at column level?

  1. unique

  2. not null

  3. check

  4. primary key
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The NOT NULL constraint can only be defined at the column level because it restricts individual column values. Constraints like UNIQUE, CHECK, and PRIMARY KEY can be defined at either column or table level, but NOT NULL is inherently column-specific.

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