有则更新无则插入
会查询两次
INSERT INTO `mydb` (`id`, `contents`,`title`)
values ('1','nenge.net','nenge') AS `new` ON DUPLICATE KEY UPDATE
`contents`=`new`.`contents`,`title`=`new`.`title`;
会查询两次
INSERT INTO `mydb` (`id`, `contents`,`title`)
values ('1','nenge.net','nenge') AS `new` ON DUPLICATE KEY UPDATE
`contents`=`new`.`contents`,`title`=`new`.`title`;