Data warehousing Code Challenges & Tips

1. Write a SQL query to find the top 3 customers with the highest total purchase amount from a sales table.

2. Create a SQL query to obtain the daily sales total for each product in a specified date range from a sales table, ordered by date.

3. Write a SQL statement to calculate the percentage growth in sales for each product month-over-month.

4. Given a table called `employees` with columns `employee_id`, `manager_id`, and `salary`, write a query to find the average salary of employees who report directly to each manager.

5. Write a SQL query to fetch the customers who have made more than 5 purchases and whose total spending exceeds $10,000, using a `GROUP BY` clause.

6. Create a SQL statement to calculate the running total of sales amounts per day in a sales table.

7. Write a SQL query to pivot sales data from a table into a format where each product type is a column and the values represent the total sales for that product type.

8. Write a SQL expression to determine the highest sales quarter for each product in the sales table, assuming the sales data spans multiple years.

9. Given a data warehouse star schema with a `fact_sales` table and `dim_date`, `dim_products`, and `dim_customers` dimensions, write a query to join these tables and return the total sales amount by year and by product.

10. Create a SQL query that implements a CTE (Common Table Expression) to find the percentage of total sales that each product contributes, ranked in descending order.