MockSQL2 Submitted

[PranathiDeepak]

No description provided.

[super30admin]

For Problem1.sql:

1. Correctness: The solution correctly identifies the first year of sales for each product using DENSE_RANK() and filters for only those records. This appears to be a correct approach for finding the first year of sales.
2. Time Complexity: The solution uses a window function (DENSE_RANK()) which typically has O(n log n) complexity where n is the number of rows in the sales table.
3. Space Complexity: The CTE creates a temporary result set, which would require O(n) space.
4. Code Quality: The code is well-structured and readable. However, using 'first_year' as a column alias in quotes is not standard SQL practice - backticks or square brackets would be more appropriate depending on the SQL dialect.
5. Efficiency: The solution is efficient for this problem. No obvious optimizations are needed.

For Problem2.sql:

1. Correctness: The solution correctly identifies customers who have purchased all products by comparing the count of distinct product keys per customer with the total count of distinct product keys. This is a valid approach.
2. Time Complexity: The GROUP BY and COUNT operations are O(n) where n is the number of records in the customer table.
3. Space Complexity: The solution uses minimal additional space beyond the input data.
4. Code Quality: The code is concise and clear. The use of HAVING with a subquery is appropriate here.
5. Efficiency: The solution is efficient. An alternative approach using JOINs might be considered for very large datasets, but this solution is perfectly acceptable.

General suggestions:

1. Consider adding comments to explain the logic, especially for more complex queries.
2. Ensure consistent formatting (e.g., spacing around operators).
3. For Problem1.sql, consider using standard SQL quoting conventions for column aliases.