在RAC环境中哪些文件存储在非共享存储上的？AC A OLR B Vote Disk C gpnp profile D OCR GG Trail文件头信息“TransInd：x02”表示的含义？D A 单条事物 B 事物中间 C 事物开始 D 事物结束 面哪个语句显示没有Email地址的教师姓名D A SELECT name FROM teacher WHERE email <> NULL; B SELECT name FROM teacher WHERE email IS NOT NULL; C SELECT name FROM teacher WHERE email = NULL; D SELECT name FROM teacher WHERE email IS NULL;