/** * Defines the set of cascadable operations that are propagated * to the associated entity. * The value cascade=ALL is ...

1.首先查看mysql是否配置了全局环境变量？ 2.如果没有配置全局变量,运行cmd 切换到.找到数据库所在bin目录下运行mysqldump 在此直接输入: mysqldump OidDB -u root -p密码 --add-drop-ta...

--MySQL按天，按周，按月，按时间段统计; Select result,count(result) as resultTotal,DATE_FORMAT(PrtTime,'%Y%m%d %H') as prtHour from degassi...

SqlServer:isnull(字段bai,0)oracle:nvl(字段,0)access:iif(isnull(字段),0,字段)mysql:ifnull(字段,0);