mysql 两表关联更新sql

sql语句：update `country2` a,country b set a.name=b.name where a.`code`=b.`code`;

表结构：

DROP TABLE IF EXISTS `country`;
CREATE TABLE `country` (
  `code` char(2) NOT NULL,
  `name` char(52) NOT NULL,
  `population` int(11) NOT NULL DEFAULT '0',
  PRIMARY KEY (`code`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

INSERT INTO country VALUES ('AU', 'Australia', '18886000');
INSERT INTO country VALUES ('BR', 'Brazil', '170115000');
INSERT INTO country VALUES ('CA', 'Canada', '1147000');
INSERT INTO country VALUES ('CN', 'China', '1277558000');
INSERT INTO country VALUES ('DE', 'Germany', '82164700');
INSERT INTO country VALUES ('FR', 'France', '59225700');
INSERT INTO country VALUES ('GB', 'United Kingdom', '59623400');
INSERT INTO country VALUES ('IN', 'India', '1013662000');
INSERT INTO country VALUES ('RU', 'Russia', '146934000');
INSERT INTO country VALUES ('US', 'United States', '278357000');

DROP TABLE IF EXISTS `country2`;
CREATE TABLE `country2` (
  `code` char(2) NOT NULL,
  `name` char(52) NOT NULL,
  `population` int(11) NOT NULL DEFAULT '0',
  PRIMARY KEY (`code`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

INSERT INTO country2 VALUES ('AU', 'Australia2', '18886000');
INSERT INTO country2 VALUES ('BR', 'Brazil2', '170115000');
INSERT INTO country2 VALUES ('CA', 'Canada2', '1147000');
INSERT INTO country2 VALUES ('CN', 'China2', '1277558000');
INSERT INTO country2 VALUES ('DE', 'Germany2', '82164700');
INSERT INTO country2 VALUES ('FR', 'France2', '59225700');
INSERT INTO country2 VALUES ('GB', 'United Kingdom2', '59623400');
INSERT INTO country2 VALUES ('IN', 'India2', '1013662000');
INSERT INTO country2 VALUES ('RU', 'Russia2', '146934000');
INSERT INTO country2 VALUES ('US', 'United States2', '278357000');

更多多表操作参考：

http://www.cnblogs.com/showonce/p/5947768.html