SQL2 submitted

[PranathiDeepak]

No description provided.

[super30admin]

1. Department_top3_Salaries.sql:

   • Correctness: The solution correctly identifies the top 3 salaries in each department using a correlated subquery approach.
   • Time Complexity: O(n^2) due to the correlated subquery comparing each employee's salary against others in the same department.
   • Space Complexity: O(n) for storing the CTE.
   • Code Quality: Well-structured with clear column aliases. Consider adding comments to explain the logic.
   • Improvement: Could potentially use window functions (DENSE_RANK()) for better performance.

2. ExchangeSeats.sql:

   • Correctness: Correctly handles the seat swapping logic for both odd and even cases.
   • Time Complexity: O(n) for the main query plus O(n) for the count subquery.
   • Space Complexity: O(1) for the count subquery result.
   • Code Quality: Good use of CASE statement. The subquery could be moved to a CTE for better readability.
   • Improvement: Consider using a window function to get the count instead of a subquery.

3. RankScores.sql:

   • Correctness: Correctly ranks scores with ties getting the same rank.
   • Time Complexity: O(n^2) due to the correlated subquery.
   • Space Complexity: O(n) for storing intermediate results.
   • Code Quality: Simple and effective. Could use window functions (DENSE_RANK()) for better performance.
   • Improvement: Window functions would be more efficient here.

4. TreeNode.sql:

   • Correctness: Correctly identifies root, leaf, and inner nodes.
   • Time Complexity: O(n) for each subquery, O(n log n) for the UNION and sorting.
   • Space Complexity: O(n) for storing intermediate results.
   • Code Quality: Clear logic with UNION operations. Could use a single CASE statement for better readability.
   • Improvement: A single query with CASE WHEN conditions might be more efficient.

General Observations:

• All solutions are correct and solve their respective problems.
• The student demonstrates good SQL knowledge but could benefit from using more modern SQL features like window functions.
• Code formatting is consistent and readable.
• Consider adding comments for complex logic.
• Some solutions could be optimized for better performance.

[super30admin]

1. Department_top3_Salaries.sql:

   • Correctness: The solution correctly identifies the top 3 salaries in each department using a correlated subquery approach. This is a valid method.
   • Time Complexity: O(n^2) due to the correlated subquery comparing each employee's salary against others in the same department.
   • Space Complexity: O(n) for storing the CTE.
   • Code Quality: The code is readable but could benefit from more descriptive column aliases (e.g., 'department_id' instead of 'did').
   • Efficiency: Could be optimized using window functions (DENSE_RANK()) for better performance.

2. ExchangeSeats.sql:

   • Correctness: The solution correctly swaps adjacent students' seats, handling both even and odd-numbered cases.
   • Time Complexity: O(n) for the main query plus O(n) for the count subquery.
   • Space Complexity: O(1) additional space beyond the input.
   • Code Quality: Well-structured with clear CASE logic. The use of MOD() is appropriate.
   • Efficiency: The solution is already efficient, though the count subquery could be moved to a CTE for better readability.

3. RankScores.sql:

   • Correctness: Correctly ranks scores with ties getting the same rank (dense ranking).
   • Time Complexity: O(n^2) due to the correlated subquery.
   • Space Complexity: O(n) for storing the result.
   • Code Quality: Simple and clear. Could use a window function (DENSE_RANK()) for better readability.
   • Efficiency: The correlated subquery approach is less efficient than window functions.

4. TreeNode.sql:

   • Correctness: Correctly identifies root, leaf, and inner nodes using UNION operations.
   • Time Complexity: O(n) for each subquery, totaling O(n) overall.
   • Space Complexity: O(n) for storing intermediate results.
   • Code Quality: Well-structured with clear UNION logic. The NULL checks are appropriate.
   • Efficiency: The solution is already efficient. No major improvements needed.

General Observations:

• The student demonstrates good understanding of SQL concepts.
• All solutions are correct and handle edge cases appropriately.
• The code is generally readable but could benefit from more consistent formatting (e.g., spacing around operators).
• Window functions could be used in some cases for better performance and readability.
• Column aliases could be more descriptive in some cases.