Dev.D

* ProblemEmployees can belong to multiple departments. When the employee joins other departments, they need to decide which department is their primary department. Note that when an employee belongs to only one department, their primary column is 'N'.Write a solution to report all the employees with their primary department. For employees who belong to one department, report their only departmen..

* ProblemFor this problem, we will consider a manager an employee who has at least 1 other employee reporting to them.Write a solution to report the ids and the names of all managers, the number of employees who report directly to them, and the average age of the reports rounded to the nearest integer.Return the result table ordered by employee_id.* ExplanationNote that we do not care about days..

* ProblemsWrite a solution to report the customer ids from the Customer table that bought all the products in the Product table.Return the result table in any order.Input: Customer table:+-------------+-------------+| customer_id | product_key |+-------------+-------------+| 1 | 5 || 2 | 6 || 3 | 5 || 3 | 6 || 1 ..

* ProblemA single number is a number that appeared only once in the MyNumberstable. Find the largest single number. If there is no single number, report null. * ExplanationMyNumbers table:+-----+| num |+-----+| 8 || 8 || 3 || 3 || 1 || 4 || 5 || 6 |+-----+Output: +-----+| num |+-----+| 6 |+-----+The single numbers are 1, 4, 5, and 6.Since 6 is the largest single number, we retu..

* ProblemWrite a solution that will, for each user, return the number of followers. Return the result table ordered by user_id in ascending order. * ExplanationThe followers of 0 are {1}The followers of 1 are {0}The followers of 2 are {0,1} * Solution (Success)# Write your MySQL query statement belowselect user_id, count(follower_id) followers_count from Followers group by user_id order ..

* ProblemWrite a solution to find all the classes that have at least five students.Return the result table in any order.* Explanation- Math has 6 students, so we include it.- English has 1 student, so we do not include it.- Biology has 1 student, so we do not include it.- Computer has 1 student, so we do not include it.* Solution (Success)SELECT classFROM CoursesGROUP BY 1HAVING COUNT(*) >= 5;

* ProblemWrite a solution to select the product id, year, quantity, and price for the first year of every product sold.Return the resulting table in any order.* Solution (Success)# Write your MySQL query statement belowwith ProductFirstYear as( select product_id, min(year) as year from Sales Group by 1)select Sales.product_id, ProductFirstYear.year as first_year, Sales.quantity,..

* ProblemWrite a solution to find the daily active user count for a period of 30 days ending 2019-07-27 inclusively. A user was active on someday if they made at least one activity on that day.Return the result table in any order. * ExplanationNote that we do not care about days with zero active users. * Solution (Success)# Write your MySQL query statement belowSELECT activity_date AS day, COU..

*Problem Write a solution to calculate the number of unique subjects each teacher teaches in the university.Return the result table in any order. *ExplanationTeacher 1: - They teach subject 2 in departments 3 and 4. - They teach subject 3 in department 3.Teacher 2: - They teach subject 1 in department 1. - They teach subject 2 in department 1. - They teach subject 3 in department 1. - They..

* ProblemWrite a solution to report the fraction of players that logged in again on the day after the day they first logged in, rounded to 2 decimal places. In other words, you need to count the number of players that logged in for at least two consecutive days starting from their first login date, then divide that number by the total number of players. * ExplanationOnly the player with id 1 log..