👉🏻FAST AND EASY TO UNDERSTAND SOLUTION || NO JOIN || GROUP BY || HAVING || MySQL
IntuitionApproachComplexity
Time complexity:

Space complexity:
Code
# Intuition
<!-- Describe your first thoughts on how to solve this problem. -->

# Approach
<!-- Describe your approach to solving the problem. -->

# Complexity
- Time complexity:
<!-- Add your time complexity here, e.g. $$O(n)$$ -->

- Space complexity:
<!-- Add your space complexity here, e.g. $$O(n)$$ -->

# Code
```mysql []
SELECT customer_id FROM Customer
GROUP BY customer_id
HAVING COUNT( DISTINCT product_key) = (
    SELECT COUNT(product_key) FROM Product
)
```
['MySQL']