Aggregate Functions Interview Questions

What is the main purpose of aggregate functions in SQL?

From an employees table (emp_id, name, department, salary, phone), write a query to show total number of employees, number of employees with phone numbers, and number of unique departments.

Which query counts the total number of students in the students table?

From a sales table (sale_id, salesperson_id, product_id, quantity, unit_price), calculate total sales amount and average sale amount per salesperson.

From an orders table (order_id, customer_id, order_date, total_amount), find the earliest order date, latest order date, lowest order amount, and highest order amount for each customer.

Which aggregate function calculates the average salary of employees?

From a products table (product_id, product_name, category, price, stock_quantity), show category-wise statistics: total products, average price, minimum price, maximum price, and total stock, but only for categories with more than 2 products.

Which query finds the maximum salary from the employees table?

How do aggregate functions handle NULL values?

Which query shows the minimum and maximum salary from the employees table?