Completed Sql2

[NehaDhaliwal]

No description provided.

[Nandha2Tech]

Great Work!

[Nandha2Tech]

Great Work!

[super30admin]

1. Problem 1.sql (Ranking Scores):

   • Correctness: The solution correctly uses dense_rank() to handle ties in scores appropriately.
   • Time Complexity: O(n log n) due to the sorting operation in dense_rank().
   • Space Complexity: O(n) for storing the result set.
   • Code Quality: Simple and clean, follows best practices.
   • Efficiency: No obvious optimizations needed for this straightforward problem.

2. Problem 2.sql (Exchange Seats):

   • Correctness: The solution handles both even and odd number of students correctly, including the edge case where the last student doesn't need to swap when the count is odd.
   • Time Complexity: O(n) for the count operation and O(n log n) for the final sorting.
   • Space Complexity: O(n) for the result set.
   • Code Quality: The CASE statement is well-structured but could be more readable with better indentation. The subquery for counting could be moved to a WITH clause for better readability.
   • Efficiency: The solution is efficient, though using a window function for the count might be slightly more elegant.

3. Problem 3.sql (Tree Node Types):

   • Correctness: Correctly identifies Root, Inner, and Leaf nodes using CASE and subqueries.
   • Time Complexity: O(n^2) due to the subquery in the CASE statement (for each row, it checks against all p_ids).
   • Space Complexity: O(n) for the result set.
   • Code Quality: Good structure, but the subquery could be moved to a JOIN for better performance and readability.
   • Efficiency: Could be optimized by using a LEFT JOIN instead of a subquery to reduce time complexity to O(n).

4. Problem 4.sql (Department Top Three Salaries):

   • Correctness: Correctly uses dense_rank() to handle ties and selects top 3 salaries per department.
   • Time Complexity: O(n log n) for the window function operation.
   • Space Complexity: O(n) for the CTE and result set.
   • Code Quality: Excellent use of CTE and window functions, very readable.
   • Efficiency: No obvious optimizations needed.

General Observations:

• The student demonstrates strong SQL skills, particularly with window functions and complex conditional logic.
• All solutions handle edge cases appropriately.
• Code formatting could be slightly improved with consistent indentation, especially in Problem 2.
• The student could consider using more JOINs instead of subqueries where possible for better performance.