Mock_SQL1 Completed

[HaswathaSridharan]

No description provided.

[super30admin]

1. Correctness:

   • For Problem 1 (Top Travellers), the solution correctly uses a LEFT JOIN to include users who haven't taken any rides, and the IFNULL function properly handles NULL values for distance. The grouping and ordering are also correct.
   • For Problem 2 (Apples & Oranges), the solution correctly calculates the difference between apple and orange sales for each date. The join condition and filtering are appropriate.

2. Time Complexity:

   • Both solutions involve JOIN operations and GROUP BY clauses, which typically have O(N log N) complexity where N is the number of rows in the tables.
   • The ordering operations add additional O(N log N) complexity.

3. Space Complexity:

   • Both solutions require space proportional to the number of rows in the result set, which is O(N) in the worst case.

4. Code Quality:

   • The code is generally well-structured and readable.
   • For Problem 2, the use of aliases 'a' and 'b' could be more descriptive (e.g., 'apple_sales' and 'orange_sales').
   • The WHERE clause in Problem 2 could be simplified to a.fruit = 'apples' and b.fruit = 'oranges' since we're checking for exact matches.
   • Consistent indentation would improve readability.

5. Efficiency:

   • Both solutions are efficient for typical SQL operations.
   • For Problem 2, an alternative approach using conditional aggregation (CASE statements) might be more readable and potentially more efficient:

     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