Technical part:
1️⃣ Given an array of numbers, find the missing numbers from the array based on the max. e.g: array = [5,2,3] should return [1,4] because 5 is the max and calculating from 1 to 5 the missing numbers from the array is 1 and 4. The return order doesnt matter.
// [5,2,3] => [1,4] OR [4,1]
2️⃣ Design DB tables for Employee and Department.
3️⃣ From the DB you just created, query for all employees named "John" and their department
4️⃣ Write another query to list departments and the number of employees in each
5️⃣ why/when to use Inner Join vs Left Join?