Done SQL 6

[sakshiasati17]

No description provided.

[super30admin]

Let me evaluate each solution one by one:

1. Combine_Two_Tables.sql:

   • Correctness: The solution correctly implements a LEFT JOIN to combine person and address data, handling cases where addresses might be missing.
   • Time Complexity: O(n) for the join operation where n is the number of records.
   • Space Complexity: O(n) for storing the result.
   • Code Quality: Clean and straightforward, following SQL best practices.
   • Efficiency: No obvious optimizations needed.

2. Customers_with_Strictly_increasing_Purchases.sql:

   • Correctness: The solution attempts to find customers with strictly increasing purchases year over year, but the logic might miss some edge cases.
   • Time Complexity: O(n^2) due to the self-join.
   • Space Complexity: O(n) for storing the CTE.
   • Code Quality: The query is a bit complex and could benefit from comments explaining the logic.
   • Efficiency: The self-join approach might be inefficient for large datasets.

3. Game_Play_Analysis_II.sql:

   • Correctness: Correctly finds the first login device for each player.
   • Time Complexity: O(n) for the subquery and O(n) for the main query.
   • Space Complexity: O(n) for storing intermediate results.
   • Code Quality: Well-structured and readable.
   • Efficiency: The IN clause with a subquery is efficient for this use case.

4. Game_Play_Analysis_III.sql:

   • Correctness: Correctly calculates running totals of games played.
   • Time Complexity: O(n log n) for the window function.
   • Space Complexity: O(n) for the window frame.
   • Code Quality: Clear and concise, using window functions appropriately.
   • Efficiency: Window functions are the optimal approach here.

5. Shortest_Distance_in_a_Plane.sql:

   • Correctness: The solution attempts to find the shortest distance but the join condition is overly complex and might not cover all cases.
   • Time Complexity: O(n^2) due to the self-join.
   • Space Complexity: O(n^2) for storing all combinations.
   • Code Quality: The join condition is hard to read and could be simplified.
   • Efficiency: The join condition could be optimized to avoid redundant comparisons.

General feedback:

• Strengths: The student demonstrates good understanding of SQL concepts like joins, window functions, and aggregations.
• Areas for improvement: Some queries could benefit from better comments explaining complex logic. The join condition in the shortest distance problem could be simplified.