DAA-C01 Question #18: Real Exam Question with Answer & Explanation

Question

What is the primary benefit of using User-Defined Functions (UDFs) in SQL for data analysis?

Options

• AThey enable customization and extension of SQL functionalities for specific data operations.
• BUDFs restrict data analysis to predefined operations.
• CUDFs can only be used with Materialized views.
• DUDFs hinder query optimization.

Explanation

Option A is correct because UDFs allow analysts to encapsulate custom logic - such as complex calculations, string transformations, or business rules - that aren't available in standard SQL, making them reusable across queries and extending what SQL can natively do.

B is wrong because it's the opposite of reality: UDFs expand what's possible, rather than restricting analysis to predefined operations. C is wrong because UDFs are independent of materialized views and can be called in any query context (SELECT, WHERE, JOIN, etc.). D is wrong because while poorly written UDFs can affect performance, UDFs themselves don't inherently hinder optimization - and this isn't their defining characteristic.

Memory tip: Think of UDFs as "SQL plugins" - just like browser plugins add features your browser doesn't have out of the box, UDFs add custom functionality that standard SQL lacks. The word User-Defined is the key: you define it, so it's customized for your needs.

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