Multiple choice technology databases

We have unique constraint on sal column on emp table. can the column accept multiple null values?

  1. True

  2. False
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A Correct answer
Explanation

Unique constraints in SQL allow multiple NULL values because NULL represents unknown or missing data, not an actual value. The uniqueness check only applies to non-NULL values - each NULL is considered distinct from other NULLs. Therefore, you can insert as many NULL values as needed into a column with a unique constraint.

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