sqlserver 删掉日志文件ldf以后 救命步骤：
先新建一个新数据库，
删掉新建的 .mdb
用想要还原的mdb覆盖
执行下面的语句
ALTER DATABASE 'DB_Core' SET RECOVERY SIMPLE;
alter database DB_Core set emergency
alter database DB_Core set single_user
dbcc checkdb('DB_Core',REPAIR_ALLOW_DATA_LOSS)
dbcc checkdb('DB_Core',REPAIR_REBUILD)
alter database 'DB_Core' set multi_user