Completed MockSQL2

[sangeeths29]

No description provided.

[super30admin]

1. Correctness:

   • For the first problem (Customers Who Bought All Products), 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 products. This approach is correct.
   • For the second problem (Product Sales Analysis III), the solution correctly identifies the first year of sales for each product and retrieves the corresponding quantity and price. The use of a subquery with MIN(year) is appropriate.

2. Time Complexity:

   • For the first problem, the solution involves a GROUP BY and a subquery, resulting in O(n) time complexity where n is the number of records in the Customer table.
   • For the second problem, the solution involves a subquery with GROUP BY and MIN, resulting in O(n) time complexity where n is the number of records in the Sales table.

3. Space Complexity:

   • Both solutions have a space complexity of O(n) due to the storage required for the intermediate results of the GROUP BY and subqueries.

4. Code Quality:

   • The code is well-structured and readable. Comments are provided to explain the purpose of each query, which is good practice.
   • For the second problem, the use of IN with a tuple (product_id, year) is a good approach, but it could be made clearer by using a JOIN instead, which might be more intuitive for some readers.

5. Efficiency:

   • Both solutions are efficient for their respective problems. However, for the second problem, using a JOIN with the subquery might be more efficient in some SQL engines, as it can avoid the overhead of the IN clause.

Potential Edge Cases:

• For the first problem, ensure that the Product table is not empty, as the subquery would return 0, and no customers would be selected.
• For the second problem, ensure that there are no NULL values in the product_id or year columns, as this could affect the results.