SQL Questions: Basic SQL Query: Write a SQL query to find the second highest salary from an employee table. JOINs: What is the difference between an INNER JOIN and a LEFT JOIN? Can you provide an example? Aggregation Functions: How would you write a SQL query to calculate the average salary of employees in each department? Subqueries: Can you explain what a correlated subquery is and give an example where it might be used? Optimization: What strategies would you use to optimize a slow-running SQL query? Python Questions: Data Structures: What are the main differences between a list and a tuple in Python? Functions: Write a Python function to reverse a string without using the built-in reverse() method. Libraries: How would you use the pandas library to handle missing data in a dataset? Exception Handling: What is the purpose of try, except, and finally in Python? Can you provide an example? Object-Oriented Programming (OOP): Explain the concept of inheritance in Python and provide a simple example. Power BI Questions: Data Transformation: How would you load data into Power BI from multiple sources and combine them into a single dataset? DAX Calculations: What is the difference between calculated columns and measures in Power BI? Can you provide examples of when to use each? Visualizations: What types of visualizations are best suited for showing trends over time in Power BI? Power Query: How would you use Power Query to clean and transform data before loading it into Power BI? Performance Optimization: What steps can you take to improve the performance of a Power BI report with large datasets?