Delete duplicate row from the table

CREATE TABLE mytb (url_id int, url_addr varchar(100));

INSERT INTO mytb VALUES (1, 'www.google.com');

INSERT INTO mytb VALUES (2, 'www.microsoft.com');

INSERT INTO mytb VALUES (3, 'www.apple.com');

INSERT INTO mytb VALUES (4, 'www.google.com');

INSERT INTO mytb VALUES (5, 'www.cnn.com');

INSERT INTO mytb VALUES (6, 'www.apple.com');

DELETE t2

FROM mytb t1

JOIN mytb t2 ON (t2.url_addr = t1.url_addr AND t2.url_id > t1.url_id);