错误信息：
Error Code: 1175. You are using safe update mode and you tried to update a table without a WHERE that uses a KEY column To disable safe mode, toggle the option in Preferences -> SQL Editor -> Query Editor and reconnect.
平台及环境：mysql 自带的workbench
问题产生条件：
set与where针对同一字段
例如：update employees set salary=50 where salary =90;
解决：
执行SET SQL_SAFE_UPDATES = 0;
备注：
同样的update语句在navicat 客户端能成功执行该语句
