games shows the year and the city hosting the Olympic Games.
DROP TABLE games
CREATE TABLE games( yr INTEGER PRIMARY KEY, city VARCHAR(20)); INSERT INTO games VALUES (2000,'Sydney'); INSERT INTO games VALUES (2004,'Athens'); INSERT INTO games VALUES (2008,'Beijing'); INSERT INTO games VALUES (2012,'London');
When you create an index you make it faster to find a particular row. You can also make the JOIN operator faster.
CREATE INDEX gamesIdx ON games(city,yr); SELECT yr, city FROM games