Oracle备份：
exp vta/vtaPwd@hrst file=D:Backupdaochu.dmp log=D:Backupdaochu.log owner=vta
Oracle恢复：
imp vtahg/vtahgPwd@hrst file=D:Backupdaochu.dmp log=D:Backupdaochu.log fromuser=vta touser=vtahg
fromuser=vta ：原用户
touser=vtahg：目标用户
Oracle查空表：
Select 'alter table '||table_name||' allocate extent;' from user_tables where num_rows=0 or num_rows is null-空表