Multiple choice technology databases

The query performance increases by using NOT operator.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Using the NOT operator in SQL queries DECREASES performance. NOT prevents the database from using indexes efficiently and forces additional negation processing. Queries using NOT (or !=, NOT IN, NOT EXISTS) are slower than their positive equivalents because they require evaluating and rejecting rows rather than directly matching them.

AI explanation

The NOT operator (and negated conditions like <>, NOT IN, NOT LIKE) typically hurts query performance rather than helping it, because most relational optimizers (including DB2) struggle to use a B-tree index efficiently for 'not equal to' style predicates — the engine often falls back to a full table/index scan to evaluate the negation. So the statement 'query performance increases by using NOT' is False; in practice you should minimize NOT and prefer positive, sargable predicates for better index usage.

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