Write a python program for the Fibonacci series and Linked list program. Write the Linux command - In the home directory, there are 100 subdirectories. Inside them, there are multiple files. Print the name of each subdirectory and the count of files in it. Write a query to print duplicates from a table. Write a query to find the second highest salary from employee table? What are views, stored procedures, and triggers?

What are JOINs in SQL?