MySQL Solution for Customers who Brought All Products Problem
Intuition\n Describe your first thoughts on how to solve this problem. \nThe intuition behind the given solution is to find customer IDs that have purchased all
# Intuition\n<!-- Describe your first thoughts on how to solve this problem. -->\nThe intuition behind the given solution is to find customer IDs that have purchased all distinct products available in the Product table. The approach involves grouping the Customer table by customer_id and then applying a condition in the HAVING clause to compare the sum of distinct product_key values for each customer with the total sum of product_key values in the Product table.\n\n# Approach\n<!-- Describe your approach to solving the problem. -->\n1. Group the rows in the Customer table by customer_id.\n1. For each group, calculate the sum of distinct product_key values.\n1. Compare the sum of distinct product_key values for each group with the total sum of product_key values in the Product table.\n1. Return the customer_id values that satisfy the condition.\n\n# Complexity\n- Time complexity:\n<!-- Add your time complexity here, e.g. $$O(n)$$ -->\nThe time complexity of this solution depends on the size of the Customer and Product tables. The grouping operation requires scanning the Customer table, which has a time complexity of O(n), where n is the number of rows in the Customer table. Additionally, calculating the sum of distinct product_key values involves aggregating and comparing values, which also has a time complexity of O(n).\n\n- Space complexity:\n<!-- Add your space complexity here, e.g. $$O(n)$$ -->\nThe space complexity of this solution depends on the number of distinct customer_id values and the number of distinct product_key values. The query requires storing the grouped customer_id values and the distinct product_key values temporarily, so the space complexity is determined by the cardinality of these values.\n\n# Code\n```\n# Write your MySQL query statement below\nselect customer_id from Customer group by customer_id\nhaving sum(distinct product_key) = \n(select sum(product_key) from Product)\n```
['MySQL']