Completed Sql5

[sangeeths29]

No description provided.

[super30admin]

1. Correctness:

   • For Problem 1 (Report Contiguous Dates), the solution correctly identifies contiguous date ranges for failed and succeeded periods using the difference between ranks technique.
   • For Problem 2 (Students Report By Geography), both approaches correctly pivot the data, though the second approach with session variables is less conventional and harder to maintain.
   • For Problem 3 (Avg Salary Departments Vs Company), the solution correctly compares department averages with company averages.
   • For Problem 4 (Game Play Analysis I), both approaches correctly find the first login date for each player.

2. Time Complexity:

   • All solutions use appropriate window functions (RANK, ROW_NUMBER) which typically run in O(n log n) time due to sorting.
   • The GROUP BY operations are efficient for the given problems.

3. Space Complexity:

   • The CTEs create temporary tables in memory, but this is reasonable for these problems.
   • The session variables approach in Problem 2 uses additional memory for variables.

4. Code Quality:

   • Good use of CTEs to break down complex queries.
   • Consistent formatting and clear comments explaining the approach.
   • The second approach in Problem 2 using session variables is less readable and maintainable.
   • Some column aliases could be more descriptive (e.g., 'rnk' could be 'rank').

5. Efficiency:

   • All solutions are efficient for their respective problems.
   • For Problem 4, the MIN approach is simpler and likely more efficient than the RANK approach.
   • Consider adding indexes on date columns and join columns for better performance with large datasets.