SQL

Finding nth Highest Salary within each department

Given a CSV file with raw customer transactions, design an ETL pipeline that cleans data, aggregates total sales by region and product, and loads into target table

Given a complex nested query, how would you refactor it for better readability and efficiency?

Given a dataset, perform transformations: Filter rows where sales > 1000, Add a new column calculating a 10% discount on sales, Group data by region and calculate total revenue.

Given a table of sales data, use window functions to calculate a running total.

Given a table with 10 records and another with 4 records, how many records result from a cross join?

Given a table with sales data, write a query to find consecutive days with decreasing revenue.

Given an unoptimized query execution plan, how would you diagnose and improve performance?