Question

Queries can use various types of operators. Which operators are swapped?

I. AND accomplishes a set intersection, in which the answer includes all instances that meet both conditions
II. NOT identifies instances that do not meet one or more conditions
III. BETWEEN is used to define the range limits by identifying records for which a field's value is within a specific range of values
IV. WHERE is used to retrieve attributes for which the value contains non null values
V. OR accomplishes a set union, in which the answer includes all instances that meet one condition and all instances that meet the other condition
VI. EXISTS specifies criteria rows of data must meet to be included in the answer

a) I and II
b) IV and VI
c) III and IV
d) V and VI

Answer 1

The swapped operators are WHERE and EXISTS, because WHERE is used to specify conditions while EXISTS is used to test for the presence of rows meeting those conditions. Thus, the answer is 'c) III and IV'.

Step-by-step explanation:

The operators in question are related to the use of Boolean operators in database queries or search logic. Let's evaluate each statement:

• I. AND operator does indeed perform a set intersection and requires both conditions to be met.
• II. NOT operator excludes instances that do meet the condition(s).
• III. BETWEEN specifies a range something must fall between, which is correct as stated.
• IV. WHERE is not used for non-null values specifically but rather to specify a condition that rows must meet. It can be used in conjunction with other operators or functions to filter for non-null values.
• V. OR performs a set union, correctly including instances that meet either condition.
• VI. EXISTS is used to test for the existence of rows that meet certain criteria, not to specify criteria themselves. Therefore, WHERE should be the operator defining the criteria, and EXISTS should be checking for the existence of rows that meet those criteria.

Based on these clarifications, the operators that are swapped in the given statements are IV (WHERE) and VI (EXISTS), so the correct answer is c) III and IV.