NOT: which operator negates a set of conditions in a WHERE clause?

NOT: which operator negates a set of conditions in a WHERE clause?

• A. Concatenating Strings
• B. ILIKE
• C. COALESCE
• D. NOT

Answer: (D)

The concept being tested is negation of a condition in a WHERE clause. The NOT operator specifically inverts the truth value of the predicate it precedes. So if a condition would include a row, applying NOT will exclude it, and vice versa. For example, WHERE NOT (salary > 100000) selects rows where salary is 100000 or less. Not only can NOT be used with simple comparisons, but it can wrap more complex predicates too, including EXISTS, IN, IS NULL, and it interacts with AND/OR via De Morgan’s laws (NOT (A AND B) equals NOT A OR NOT B, and NOT (A OR B) equals NOT A AND NOT B). In contrast, concatenating strings is simply combining text, ILIKE does pattern matching, and COALESCE picks the first non-null value—none of these are the dedicated negation operator. Therefore, the operator that negates a set of conditions is NOT.

The concept being tested is negation of a condition in a WHERE clause. The NOT operator specifically inverts the truth value of the predicate it precedes. So if a condition would include a row, applying NOT will exclude it, and vice versa. For example, WHERE NOT (salary > 100000) selects rows where salary is 100000 or less. Not only can NOT be used with simple comparisons, but it can wrap more complex predicates too, including EXISTS, IN, IS NULL, and it interacts with AND/OR via De Morgan’s laws (NOT (A AND B) equals NOT A OR NOT B, and NOT (A OR B) equals NOT A AND NOT B). In contrast, concatenating strings is simply combining text, ILIKE does pattern matching, and COALESCE picks the first non-null value—none of these are the dedicated negation operator. Therefore, the operator that negates a set of conditions is NOT.