Add some commonly asked SQL nested or subquery problems in interviews

[Sar-taj107]

if you familiar with SQL and have good understanding or command on Database add some commonly asked SQL nested or subquery problems in interviews, along with brief explanations and example if possible. and also write query for each of them few of the example are:

Find the second highest salary from the employee table.
Find employees whose salary is greater than the average salary of all employees.
List the employees who work in the same department as an employee named 'John'.
Display departments that have no employees assigned.
For each department, find the employee with the highest salary.
List employees who do not have a manager assigned.
Find the Nth highest salary in the employee table.