When is it appropriate to use a distinct query?

Using a distinct query is appropriate when you need a unique list of information. The purpose of a distinct query is to eliminate duplicate entries from the result set, ensuring that each value returned appears only once. This is particularly useful when you are working with large datasets that may contain repeated values across a particular field, and you want to analyze or present a clear, concise list without redundancy.

For example, if you have a database of customer transactions and you want to know which products have been sold without listing any duplicates, employing a distinct query would enable you to retrieve only unique product names. This can facilitate better insight into product offerings or trends without the clutter of repeated entries.

In situations where aggregation is required, such as summarizing data into totals or averages, a distinct query may not suffice on its own, since it focuses only on uniqueness rather than summarization. Similarly, filtering data based on dates involves selecting records that meet certain criteria without necessarily needing uniqueness. Finally, when multiple entries for each record are desired, a distinct query would not be suitable, because it would restrict the output to unique instances only.