For complex SQL queries involving multiple steps of data transformation and calculation, when would a Common Table Expression (CTE) be a superior choice over a nested subquery for clarity and maintenance?

For complex SQL queries involving multiple steps of data transformation and calculation, a Common Table Expression (CTE) is a superior choice over a nested subquery for clarity and maintenance because it provides a sequential, top-down approach to query construction, enhancing readability and simplifying modifications. A Common Table Expression, defined using the `WITH` clause, creates a temporary, named result set that can be referenced within a single SQL statement. This allows a complex query to be broken down into distinct, logical, and named steps, where the output of one CTE can serve as the input for a subsequent CTE. This modularity directly addresses clarity by presenting the data transformation process as a clear, step-by-ste....