Mock SQL 2

[hinduja97]

No description provided.

[super30admin]

The student's solution demonstrates a good understanding of SQL queries and problem-solving approaches. Here's a detailed evaluation:

1. CustomersWho.sql:

   • Correctness: The query correctly identifies customers who have bought all products by comparing distinct product counts with the total product count.
   • Time Complexity: O(n) where n is the number of records in the customer table (assuming proper indexing).
   • Space Complexity: Minimal as it only needs to store intermediate results for the group by and having clauses.
   • Code Quality: Clean and concise, follows best practices.
   • Efficiency: Well-optimized as it uses a single pass through the data with aggregation.

2. ProductAnalysis.sql:

   • Solution 1:
     • Correctness: Correctly identifies first year sales using DENSE_RANK().
     • Time Complexity: O(n log n) due to the window function sorting.
     • Space Complexity: Higher due to window function creating additional data structures.
     • Code Quality: Readable but window functions can be expensive.
   • Solution 2:
     • Correctness: Correct alternative approach using GROUP BY and JOIN.
     • Time Complexity: O(n) for the group by and O(n) for the join (assuming proper indexing).
     • Space Complexity: Lower than Solution 1 as it doesn't use window functions.
     • Code Quality: Well-structured and efficient.
   • Both solutions are correct, but Solution 2 is more efficient for this specific problem.

General Observations:

• The student shows good problem-solving skills by providing multiple solutions.
• The code is well-formatted and easy to read.
• The README.md is empty - it would be good practice to include a brief problem description.

Areas for Improvement:

• For ProductAnalysis.sql, Solution 1 could be noted as less efficient due to window function overhead.
• Adding comments explaining the approach would be helpful for maintainability.
• The empty README.md could be improved with documentation.