Done Mock SQL 3

[sagar1023]

No description provided.

[super30admin]

1. Correctness:

   • For the first query (Market Analysis II), the solution attempts to find the second item sold by each seller, but it has several issues. The RIGHT JOIN with Items seems unnecessary since we're interested in sellers (Users) and their orders. The WHERE clause filters for num=2, which would miss sellers who haven't sold any items or only sold one item. The output columns don't clearly match what would typically be expected for a market analysis problem.
   • For the second query (Tournament Winners), the solution correctly identifies the winner for each group based on total score and uses RANK() appropriately. However, the MIN(id) in the final SELECT could be misleading if there are multiple players with the same top score in a group.

2. Time Complexity:

   • Both queries use window functions (ROW_NUMBER() and RANK()) which typically operate in O(n log n) time where n is the number of rows.
   • The joins and GROUP BY operations also contribute to the overall time complexity, making both queries approximately O(n log n).

3. Space Complexity:

   • The CTEs create temporary tables in memory, so space complexity is O(n) for storing intermediate results.
   • The window functions also require additional space for sorting and ranking operations.

4. Code Quality:

   • The queries lack proper indentation and formatting, making them harder to read.
   • Column aliases like 'num' and 'f_b' are not descriptive.
   • The first query mixes different concerns (joining Items when it's not clearly needed).
   • The second query is better structured but could benefit from more descriptive CTE names.

5. Efficiency:

   • For the first query, consider starting from Users table and LEFT JOIN to Orders to ensure all users are included.
   • For both queries, consider whether all selected columns are necessary in the final output.
   • The use of RIGHT JOIN in the first query is unusual and often harder to understand than LEFT JOIN.