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The Pareto Principle, commonly known as the 80/20 rule, argues that 80% of the results are achieved with 20% of the effort. Joseph M. Juran introduced this idea, which was influenced by Vilfredo Pareto, an Italian economist who discovered that 20% of the people controlled 80% of the land in Italy. Over time, this approach … Read more
This question was asked in Facebook interview, Ask is to give page recommendation for user1 based on Friendship and Likes. Source: LeetCode Difficulty: Medium Company: Facebook Page Recommendations Q. Write an SQL query to recommend pages to the user with user_id = 1 using the pages that your friends liked. It should not recommend pages you already liked. … Read more
Company: BlackRock CTC: 26LPA Source: Linked Post Q. Retrieve the name of the manager who supervises the most employees. Solution: Explanation: Here, we want to find out the manager who supervises the most employees. To achieve this, the query works in the following steps: Key Logic: Summary: The query counts how many employees each manager supervises, … Read more
Company: BlackRock CTC: 26LPA Source: Linked Post Q: Write a query to calculate the median salary of employees in a table. Solution: Explanation: Here we need to find out the median salary from the employees table. To calculate the median salary, we need some essential information, like the total number of employees in the table. … Read more
Query: SELECT product_id FROM sales GROUP BY product_id HAVING COUNT(DISTINCT region_id) = (SELECT COUNT(*) FROM regions); Explanation: We need to find products that have been sold in all regions. This involves comparing the distinct regions a product appears in with the total number of regions available. Here’s how the query works step-by-step: Key Points: Example: … Read more
