- How many cities are there in city table?
- How many unique cities are there?
- Find duplicate cities name ?
- Find the number of orders in each year?
- Find the monthly sales of year 2017?
- Find top 2 months in which we have high sales in year 2016?
- Find top 2 months in which we have low sales in year 2017?
- Extract country code from id of orders table
- Extract catgeory from product_id
- Count how many product we have sold in total for each category. *You only need to use orders table.