How would you modify this query to rank students by score within each class, but ensure no gaps in ranks?

hard📝 Application Q9 of 15

PostgreSQL - Window Functions in PostgreSQL

SELECT student_id, class_id, RANK() OVER (PARTITION BY class_id ORDER BY score DESC) AS rank FROM students;

AAdd ROW_NUMBER() instead of RANK()

BReplace RANK() with DENSE_RANK()

CRemove PARTITION BY clause

DUse COUNT() OVER instead of RANK()

Step-by-Step Solution

Solution:

Step 1: Identify issue with RANK() gaps
RANK() leaves gaps in ranking when ties occur.
Step 2: Use DENSE_RANK() to avoid gaps
DENSE_RANK() assigns consecutive ranks without gaps within each partition.
Final Answer:
Replace RANK() with DENSE_RANK() -> Option B
Quick Check:
DENSE_RANK removes gaps in partitioned ranking = Replace RANK() with DENSE_RANK() [OK]

Quick Trick: Use DENSE_RANK() for gapless ranks within groups [OK]

Common Mistakes:

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