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
SQLhard
3
Given a complex nested query, how would you refactor it for better readability and efficiency?
SQLmedium
4
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.
SQLeasy
5
Given a table of sales data, use window functions to calculate a running total.
SQLmedium
6
Given a table with 10 records and another with 4 records, how many records result from a cross join?
SQLmedium
7
Given a table with sales data, write a query to find consecutive days with decreasing revenue.
SQLmedium
8
Given an unoptimized query execution plan, how would you diagnose and improve performance?
SQLmedium
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