What is the function of the IN operator in query expressions?

The function of the IN operator in query expressions is centered around its ability to compare a field against a list of constant values. When utilizing the IN operator, you can check if a certain value matches any value within a specified set. This is particularly useful in scenarios where you want to filter records based on multiple values without needing to write extensive OR conditions. For example, if you want to find records where a status field is either 'active', 'pending', or 'closed', using the IN operator allows you to succinctly express this requirement. By specifying these values within parentheses, the query efficiently retrieves results that satisfy this condition, enhancing both clarity and performance in data retrieval tasks.

In contrast, the other options address different functions that do not align with the purpose of the IN operator. For instance, adding numeric values pertains to basic arithmetic operations, while performing logical operations is generally associated with operators such as AND, OR, and NOT. Returning a boolean value based on conditions relates more to conditional statements or logical checks rather than direct comparisons of multiple constants within a field.