CREATE TABLE web_client_accelerator (id DECIMAL, name TEXT, operating_system TEXT, client TEXT, connection TEXT)
CREATE TABLE browser (id DECIMAL, name TEXT, market_share DECIMAL)
CREATE TABLE accelerator_compatible_browser (accelerator_id DECIMAL, browser_id DECIMAL, compatible_since_year DECIMAL)

Find the number of web accelerators used for each Operating system.
SELECT operating_system, COUNT(*) FROM web_client_accelerator GROUP BY operating_system
SELECT "operating_system", COUNT(*) FROM "web_client_accelerator" GROUP BY "operating_system"