Completed Sql5

[kaaviyavarrshini]

No description provided.

[super30admin]

Let me evaluate each solution one by one:

1. Problem1_ContiguousDate.sql:

• Correctness: The solution correctly identifies contiguous date periods for failed and succeeded states using the difference between row numbers technique. This is a standard approach for such problems.
• Time Complexity: O(n log n) due to sorting operations.
• Space Complexity: O(n) for storing intermediate results.
• Code Quality: Well-structured with clear CTEs. The column alias 'dat' could be more descriptive like 'date_value'.
• Efficiency: The solution is efficient for this problem type. No major optimizations needed.

2. Problem2_StudentReportByGeography.sql:

• Correctness: Both solutions correctly pivot the data by continent. Solution 2 using session variables is more advanced but achieves the same result.
• Time Complexity: O(n log n) for sorting operations in both solutions.
• Space Complexity: O(n) for storing intermediate results.
• Code Quality: Solution 1 is more readable with clear CTEs. Solution 2 is clever but harder to maintain due to session variables.
• Efficiency: Both solutions are efficient. Solution 1 is preferable for readability unless performance is critical.

3. Problem3_AvgSalarDepComp.sql:

• Correctness: Correctly compares department averages with company averages using proper date formatting.
• Time Complexity: O(n) for the aggregations.
• Space Complexity: O(n) for storing intermediate results.
• Code Quality: Well-structured with clear CTEs. The lpad for month formatting is a nice touch.
• Efficiency: The solution is efficient. No major optimizations needed.

4. Problem4_GamePlay1.sql:

• Correctness: Correctly finds the first login date for each player.
• Time Complexity: O(n) for the grouping operation.
• Space Complexity: O(n) for storing results.
• Code Quality: Simple and effective. No improvements needed.
• Efficiency: Optimal solution for this problem.

General strengths:

• Good use of window functions and CTEs
• Proper handling of date formatting
• Multiple approaches shown for some problems
• Clear and consistent formatting

Areas for improvement:

• Could add more comments explaining the logic in complex queries
• Some column aliases could be more descriptive
• Solution 2 in Problem2 could be simplified for better readability