Can I Use ORDER BY in a Subquery?

Can You Use an Order By Clause in a Subquery?

Conceptual Considerations:

Using an order by clause in a subquery may not conceptually make sense. The subquery's results will be utilized in an outer query, which will eventually require ordering. Therefore, ordering the subquery separately is unnecessary.

Technical Considerations:

SQL query results are inherently unordered. Even if you employ an order by clause in a subquery, the order of the results returned from the outer query remains indeterminate. Ordering the subquery becomes meaningless.

Implementation-Specific Differences:

Specific RDBMS implementations may exhibit varying behavior due to optimizations. However, relying on such implementation-specific behavior is strongly discouraged.

Exceptions:

When utilizing TOP or LIMIT in a subquery, it is essential to include an order by clause. However, these constructs are not standardized in SQL and may not be universally supported.

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