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

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"