CREATE TABLE stock (shop_id DECIMAL, device_id DECIMAL, quantity DECIMAL)
CREATE TABLE device (device_id DECIMAL, device TEXT, carrier TEXT, package_version TEXT, applications TEXT, software_platform TEXT)
CREATE TABLE shop (shop_id DECIMAL, shop_name TEXT, location TEXT, open_date TEXT, open_year DECIMAL)

How many different software platforms are there for devices?
SELECT COUNT(DISTINCT software_platform) FROM device
SELECT COUNT(DISTINCT "software_platform") FROM "device"