Question

Queries can use various types of operators. Which operator is incorrectly described?

1) AND accomplishes a set intersection, in which the answer includes all instances that meet both conditions
2) NOT identifies instances that do not meet one or more conditions
3) BETWEEN is used to define the range limits by identifying records for which a field's value is within a specific range of values
4) EXISTS specifies criteria rows of data must meet to be included in the answer
5) OR accomplishes a set union, in which the answer includes all instances that meet one condition and all instances that meet the other condition

Answer 1

The operator incorrectly described is number 4, EXISTS, which is used to test for the existence of any record in a subquery.

Step-by-step explanation:

Among the described operators, the operator that is incorrectly described is number 4: EXISTS. The EXISTS operator is used in SQL to test for the existence of any record in a subquery. It returns true if the subquery returns one or more records. The descriptions for the AND, NOT, BETWEEN, and OR operators are correct:

• AND narrows search results to include all instances that meet both conditions, which is a set intersection.
• NOT excludes instances that meet the given condition, helping to narrow down the search result.
• BETWEEN chooses records where a field's value is inside a specified range.
• OR broadens search results, including all instances that meet either of the conditions, which is a set union.