From 1900 to 1992, how many games did London host?
From 1900 to 1992 refers to games_year BETWEEN 1900 AND 1992; London refers to city_name = 'London'; games refer to games_name;
SELECT COUNT(T3.id) FROM games_city AS T1 INNER JOIN city AS T2 ON T1.city_id = T2.id INNER JOIN games AS T3 ON T1.games_id = T3.id WHERE T2.city_name = 'London' AND T3.games_year BETWEEN 1900 AND 1992