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Identify the error in this window frame clause:

medium📝 Debug Q14 of 15
PostgreSQL - Window Functions in PostgreSQL
Identify the error in this window frame clause:
SUM(amount) OVER (ORDER BY date ROWS BETWEEN CURRENT ROW AND 3 PRECEDING)
AThe clause is syntactically correct.
BROWS cannot be used with ORDER BY date.
CSUM cannot be used as a window function.
DThe frame boundaries are reversed; '3 PRECEDING' should come before 'CURRENT ROW'.
Step-by-Step Solution
Solution:

  1. Step 1: Check frame boundary order

    Frame boundaries must go from earlier to later, so '3 PRECEDING' should be before 'CURRENT ROW'.

  2. Step 2: Validate syntax correctness

    Using ROWS with ORDER BY date and SUM is valid, so no other syntax errors.

  3. Final Answer:

    The frame boundaries are reversed; '3 PRECEDING' should come before 'CURRENT ROW'. -> Option D

  4. Quick Check:

    Frame boundaries order matters [OK]
Quick Trick: Frame start must be before frame end [OK]
Common Mistakes:
  • Reversing frame boundaries
  • Thinking ROWS can't use ORDER BY
  • Misunderstanding window function usage

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