MockSQL1 Submitted

[PranathiDeepak]

No description provided.

[super30admin]

Let me evaluate each solution separately.

Problem1.sql:

1. Correctness: The solution appears correct for calculating total distance traveled by each user, including users with no rides (handled by LEFT JOIN and IFNULL).
2. Time Complexity: O(n + m) where n is number of users and m is number of rides, due to the GROUP BY operation.
3. Space Complexity: O(n) for storing the CTE results.
4. Code Quality: Well-structured with clear CTE usage. Good practice to include both id and name in GROUP BY for consistency.
5. Efficiency: Could potentially use a subquery instead of CTE for such a simple case, but CTE is more readable.

Problem2.sql:

1. Correctness: The solution correctly calculates the difference between apples and oranges sold per date, but has a potential issue - it assumes exactly one apple and one orange record per date.
2. Time Complexity: O(n^2) due to the self-join without proper indexing conditions.
3. Space Complexity: O(n) for the result set.
4. Code Quality: Could be improved with explicit JOIN syntax and better aliases. The WHERE clause mixing join conditions with filters is not ideal.
5. Efficiency: Could be optimized with a pivot approach or conditional aggregation:

   SELECT sale_date,
          SUM(CASE WHEN fruit = 'apples' THEN sold_num ELSE 0 END) - 
          SUM(CASE WHEN fruit = 'oranges' THEN sold_num ELSE 0 END) AS diff
   FROM sales
   GROUP BY sale_date
   ORDER BY sale_date
   

General improvements needed:

1. Problem2.sql needs better handling of potential missing records for either fruit.
2. Both solutions could benefit from comments explaining the approach.
3. Consistent formatting (Problem1.sql has better formatting than Problem2.sql).