MySQL 添加外键约束,不检查现有数据

这可能是MySQL在InnoDB中设置了foreign key关联，造成无法更新或删除数据。可以通过设置FOREIGN_KEY_CHECKS变量来避免这种情况。

SET FOREIGN_KEY_CHECKS = 0;

alter table Freight_Dispatcher_Country_Mapping add constraint FK_Reference_f4 foreign key (DispatcherID) references Freight_Dispatcher (ID) on delete restrict on update restrict;

alter table Freight_Dispatcher_Culture add constraint FK_Reference_f3 foreign key (DispatcherID) references Freight_Dispatcher (ID) on delete restrict on update restrict;

SET FOREIGN_KEY_CHECKS = 1;

其他： 
关闭唯一性校验 
set unique_checks=0; 
set unique_checks=1;