Completed MockSQL3

[sangeeths29]

No description provided.

[super30admin]

The student's solution demonstrates good understanding of SQL concepts and problem-solving approach. Here's a detailed evaluation:

1. Correctness:

• For Problem 1 (Tournament Winners), the solution correctly groups players, calculates total scores, and ranks them within groups. The use of DENSE_RANK() is appropriate.
• For Problem 2 (Market Analysis II), the solution attempts to find the second favorite item, but there might be edge cases not handled (like users with less than 2 orders).

2. Time Complexity:

• Both solutions use appropriate joins and window functions which are generally efficient in SQL.
• The complexity is reasonable for typical database operations (O(n log n) for sorting/ranking operations).

3. Space Complexity:

• The CTEs create temporary tables, but this is standard practice in SQL for readability.
• Space usage is appropriate for the problem sizes.

4. Code Quality:

• Good use of CTEs for breaking down complex queries.
• Clear column aliasing and formatting.
• Could improve by adding comments explaining the purpose of each CTE step.

5. Efficiency:

• For Problem 1, the GROUP BY in rankedplayers CTE might be redundant since we're already grouping in sumscores.
• For Problem 2, the LEFT JOIN might return NULLs for users with no orders, which should be handled (currently returns NULL for 2nd_item_fav_brand).

Areas for Improvement:

• Handle edge cases better (users with no orders or only 1 order in Problem 2).
• Consider adding explicit NULL handling in the CASE statement for Problem 2.
• The GROUP BY in rankedplayers CTE (Problem 1) could be simplified.