尝试这个：
UPDATE business AS bINNER JOIN business_geopre AS g ON b.business_id = g.business_idSET b.mapx = g.latitude, b.mapy = g.longitudeWHERe (b.mapx = '' or b.mapx = 0) and g.latitude > 0
更新：
既然您说查询产生了语法错误，所以我创建了一些可以对其进行测试的表，并确认查询中没有语法错误：
mysql> create table business (business_id int unsigned primary key auto_increment, mapx varchar(255), mapy varchar(255)) engine=innodb;Query OK, 0 rows affected (0.01 sec)mysql> create table business_geopre (business_geopre_id int unsigned primary key auto_increment, business_id int unsigned not null, latitude varchar(255) not null, longitude varchar(255) not null, foreign key (business_id) references business(business_id)) engine=innodb;Query OK, 0 rows affected (0.01 sec)mysql> UPDATE business AS b -> INNER JOIN business_geopre AS g ON b.business_id = g.business_id -> SET b.mapx = g.latitude, -> b.mapy = g.longitude -> WHERe (b.mapx = '' or b.mapx = 0) and -> g.latitude > 0;Query OK, 0 rows affected (0.00 sec)Rows matched: 0 Changed: 0 Warnings: 0
看到？没有语法错误。我针对MySQL 5.5.8进行了测试。
