ROUND & Numeric Functions

-- Round average order value to 2 decimal places
SELECT ROUND(AVG(total_amount), 2) AS avg_order FROM orders;

-- Revenue summary with proper rounding
SELECT
  ROUND(SUM(amount), 2) AS total_revenue,
  ROUND(AVG(amount), 2) AS avg_payment,
  ROUND(MAX(amount) - MIN(amount), 2) AS price_range
FROM payments;

-- Discount percentage (avoid division by zero)
SELECT
  name,
  price,
  499.99 AS sale_price,
  ROUND((price - 499.99) / NULLIF(price, 0) * 100, 1) AS discount_pct
FROM products WHERE price > 499.99;

-- FLOOR and CEIL
SELECT
  FLOOR(price) AS floor_price,
  CEIL(price) AS ceil_price,
  ROUND(price) AS rounded_price
FROM products;

-- ABS: absolute difference from target price
SELECT name, ABS(price - 500) AS distance_from_500
FROM products
ORDER BY distance_from_500;

-- MOD: alternate rows (even/odd IDs)
SELECT id, name FROM products WHERE MOD(id, 2) = 0;  -- even IDs