Explain window functions. What is the difference between ROW_NUMBER(), RANK(), and DENSE_RANK()?

How would you find the running total of sales by date?

What causes poor SQL query performance, and how would you optimize a slow query?

What is the difference between OLTP and OLAP systems?

How would you handle slowly changing dimensions (SCD) in a data warehouse?

Question

Explain window functions. What is the difference between ROW_NUMBER(), RANK(), and DENSE_RANK()?

How would you find the running total of sales by date?

What causes poor SQL query performance, and how would you optimize a slow query?

What is the difference between OLTP and OLAP systems?

How would you handle slowly changing dimensions (SCD) in a data warehouse?

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