Questions:
01. Find the sales in terms of total dollars for all orders in each year, ordered from greatest to least. Do you notice any trends in the yearly sales totals?
02. Which month did Parch & Posey have the greatest sales in terms of total dollars? Are all months evenly represented by the dataset?
03. Which year did Parch & Posey have the greatest sales in terms of total number of orders? Are all years evenly represented by the dataset?
04. Which month did Parch & Posey have the greatest sales in terms of total number of orders? Are all months evenly represented by the dataset?
05. In which month of which year did Walmart spend the most on gloss paper in terms of dollars?

Question 01.
SELECT DATE_PART('year', o.occurred_at) AS year, SUM(total_amt_usd) AS total
FROM orders o
GROUP BY year
ORDER BY total DESC

Question 02.
SELECT DATE_PART('month', o.occurred_at) AS month, SUM(total_amt_usd) AS total
FROM orders o
GROUP BY month
ORDER BY total DESC

if we look closer, 2013 and 2017 have only one month, to gather more precise data we ensure to look after 2013.
SELECT DATE_PART('month', o.occurred_at) AS month, SUM(total_amt_usd) AS total
FROM orders o
WHERE o.occurred_at BETWEEN '2014-01-01' AND '2017-01-01'
GROUP BY month
ORDER BY total DESC

Question 03.
SELECT DATE_PART('year', o.occurred_at) AS year, COUNT(*) AS orders
FROM orders o
GROUP BY year
ORDER BY orders DESC

Question 04.
SELECT DATE_PART('month', o.occurred_at) AS month, COUNT(*) AS orders
FROM orders o
WHERE o.occurred_at BETWEEN '2014-01-01' AND '2017-01-01'
GROUP BY month
ORDER BY orders DESC

Question 05.
SELECT DATE_PART('year', o.occurred_at) AS year, DATE_PART('month', o.occurred_at) AS month, SUM(gloss_amt_usd) AS orders
FROM orders o
JOIN accounts a
ON o.account_id = a.id
WHERE a.name = 'Walmart'
GROUP BY year, month
ORDER BY orders DESC
LIMIT(1);