Multiple choice technology databases

What is the result if two NULL values are compared to each other?

  1. True

  2. False

  3. NULL

  4. Undefined
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C Correct answer
Explanation

NULL represents an unknown or missing value. Any comparison involving NULL (including NULL = NULL) returns NULL, not TRUE or FALSE. This is three-valued logic. The IS NULL or IS NOT NULL operators must be used to test for NULL values.

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