Why does ROW_NUMBER() assign different row numbers each time you run a query without a deterministic ORDER BY clause?

hard📝 Conceptual Q10 of 15

SQL - Window Functions Fundamentals

Why does ROW_NUMBER() assign different row numbers each time you run a query without a deterministic ORDER BY clause?

ABecause ROW_NUMBER() caches results and reuses old numbers

BBecause ROW_NUMBER() always resets to 1 for every query run

CBecause without a fixed ORDER BY, row order is not guaranteed, so numbering can vary

DBecause ROW_NUMBER() ignores ORDER BY and assigns numbers randomly

Step-by-Step Solution

Solution:

Step 1: Understand importance of ORDER BY in ROW_NUMBER()
ROW_NUMBER() depends on ORDER BY to assign consistent row numbers.
Step 2: Explain effect of missing or non-deterministic ORDER BY
Without a deterministic ORDER BY, the database can return rows in any order, causing row numbers to differ each run.
Final Answer:
Because without a fixed ORDER BY, row order is not guaranteed, so numbering can vary -> Option C
Quick Check:
ROW_NUMBER() needs deterministic ORDER BY for consistent numbering [OK]

Quick Trick: Always use deterministic ORDER BY for stable ROW_NUMBER() results [OK]

Common Mistakes:

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