The UPDATE statement can be used to change a values in rows that already exists.
In this example we move the 2012 games from London to Paris.

UPDATE games SET city='Paris' WHERE yr = 2012; SELECT * FROM games;
DROP TABLE games CREATE TABLE games(yr INT, city VARCHAR(20)); INSERT INTO games(city,yr) VALUES ('Sydney',2000); INSERT INTO games(city,yr) VALUES ('Athens',2004); INSERT INTO games(city,yr) VALUES ('Beijing',2008); INSERT INTO games(city,yr) VALUES ('London',2012);

UPDATE games SET city='Paris' WHERE yr = 2012;
SELECT * FROM games;