Did you know that the average return from investing in stocks is 10% per year (not accounting for inflation)? But who wants to be average?!
You have been asked to support an investment firm by analyzing trends in high-growth companies. They are interested in understanding which industries are producing the highest valuations and the rate at which new high-value companies are emerging. Providing them with this information gives them a competitive insight as to industry trends and how they should structure their portfolio looking forward.
You have been given access to their unicorns database, which contains the following tables:
dates
| Column | Description | 
|---|---|
company_id | A unique ID for the company. | 
date_joined | The date that the company became a unicorn. | 
year_founded | The year that the company was founded. | 
funding
| Column | Description | 
|---|---|
company_id | A unique ID for the company. | 
valuation | Company value in US dollars. | 
funding | The amount of funding raised in US dollars. | 
select_investors | A list of key investors in the company. | 
industries
| Column | Description | 
|---|---|
company_id | A unique ID for the company. | 
industry | The industry that the company operates in. | 
companies
| Column | Description | 
|---|---|
company_id | A unique ID for the company. | 
company | The name of the company. | 
city | The city where the company is headquartered. | 
country | The country where the company is headquartered. | 
continent | The continent where the company is headquartered. | 
The output
Your query should return a table in the following format:
| industry | year | num_unicorns | average_valuation_billions | 
|---|---|---|---|
| industry1 | 2021 | --- | --- | 
| industry2 | 2020 | --- | --- | 
| industry3 | 2019 | --- | --- | 
| industry1 | 2021 | --- | --- | 
| industry2 | 2020 | --- | --- | 
| industry3 | 2019 | --- | --- | 
| industry1 | 2021 | --- | --- | 
| industry2 | 2020 | --- | --- | 
| industry3 | 2019 | --- | --- | 
Where industry1, industry2, and industry3 are the three top-performing industries.
-- unicorns in years 2019-2021
SELECT
	company_id,
	EXTRACT(year FROM date_joined) AS unicorn_year
FROM dates
WHERE EXTRACT(year FROM date_joined) BETWEEN 2019 AND 2021
LIMIT 5--top_3_industries_2019_2021
	SELECT
		industry
	FROM (SELECT
			company_id,
			EXTRACT(year FROM date_joined) AS unicorn_year
		FROM dates
		WHERE EXTRACT(year FROM date_joined) BETWEEN 2019 AND 2021
		) AS u
	LEFT JOIN industries AS i
	ON i.company_id = u.company_id
	GROUP BY industry
	HAVING COUNT(u.company_id) >0
	ORDER BY COUNT(u.company_id) DESC
	LIMIT 3WITH top_3_industries_2019_2021 AS (
	SELECT
		industry
	FROM (SELECT
			company_id,
			EXTRACT(year FROM date_joined) AS unicorn_year
		FROM dates
		WHERE EXTRACT(year FROM date_joined) BETWEEN 2019 AND 2021
		) AS u
	LEFT JOIN industries AS i
	ON i.company_id = u.company_id
	GROUP BY industry
	HAVING COUNT(u.company_id) >0
	ORDER BY COUNT(u.company_id) DESC
	LIMIT 3
),
	
unicorns_in_2019_2021 AS (
	SELECT
		company_id,
		EXTRACT(year FROM date_joined) AS unicorn_year
	FROM dates
	WHERE EXTRACT(year FROM date_joined) BETWEEN 2019 AND 2021)
SELECT
	top3.industry,
	unicorn_year AS year,
	count(u.company_id) as num_unicorns,
	ROUND(AVG(valuation/1000000000),2) AS average_valuation_billions
FROM top_3_industries_2019_2021 AS top3
INNER JOIN industries AS ind
	ON top3.industry = ind.industry
INNER JOIN unicorns_in_2019_2021 AS u
	ON ind.company_id = u.company_id
INNER JOIN funding AS f
	ON u.company_id = f.company_id
GROUP BY top3.industry, unicorn_year
ORDER BY year desc, num_unicorns desc;