当误删除表空间数据文件（特指非关键数据文件，而不是关键数据文件），则可以在不备份就可以修复数据文件，但有个前提，即不能关库，假如已经关库了，则没有备份，只能offline再删除表空间；
实验如下：
1：创建测试表空间
SYS@ORA11GR2>create tablespace ts_test datafile '/u01/app/oracle/oradata/ORA11GR2/test.dbf' size 20m autoextend on;
Tablespace created
2：在测试表空间上创建测试表
SYS@ORA11GR2>create table t1 tablespace ts_test as select 1 id from dual;
Table created.
3：删除数据文件
[oracle@wang ~]$ cd /u01/app/oracle/oradata/ORA11GR2/
[oracle@wang ORA11GR2]$ ls
control01.ctl redo01.log sysaux01.dbf test.dbf
control02.ctl redo02.log system01.dbf undotbs01.dbf
example01.dbf redo03.log temp01.dbf users01.dbf
[oracle@wang ORA11GR2]$
[oracle@wang ORA11GR2]$ ls test.dbf
test.dbf
[oracle@wang ORA11GR2]$ rm test.dbf
[oracle@wang ORA11GR2]$
4：再创建表，验证，数据文件已丢失
SYS@ORA11GR2>create table t2 tablespace ts_test as select 1 id from dual;
Table created.
SYS@ORA11GR2>exit
[oracle@wang ~]$ sqlplus / as sysdba
SQL*Plus: Release 11.2.0.4.0 Production on Wed Oct 12 23:26:22 2016
Copyright (c) 1982, 2013, Oracle. All rights reserved.
Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
SYS@ORA11GR2>drop table t2 purge;
drop table t2 purge
*
ERROR at line 1:
ORA-01116: error in opening database file 6
ORA-01110: data file 6: '/u01/app/oracle/oradata/ORA11GR2/test.dbf'
ORA-27041: unable to open file
Linux-x86_64 Error: 2: No such file or directory
Additional information: 3
5：切记，此时，不能关闭数据库
6：查看DBWR进程的pid
[oracle@wang ~]$ ps -ef | grep dbw|grep -v grep
oracle 899 1 0 10:59 ? 00:00:11 ora_dbw0_ORA11GR2
oracle 29549 1 0 Oct11 ? 00:00:03 ora_dbw0_SF
7：找到句柄 请参阅此链接http://www.cnblogs.com/cute/archive/2011/04/20/2022280.html
[oracle@wang ~]$ ll -rt /proc/899/fd
total 0
lr-x------ 1 oracle oinstall 64 Oct 12 23:29 6 -> /u01/app/oracle/product/11.2.0/dbhome_1/rdbms/mesg/oraus.msb
lr-x------ 1 oracle oinstall 64 Oct 12 23:29 5 -> /dev/null
lr-x------ 1 oracle oinstall 64 Oct 12 23:29 4 -> /dev/null
lr-x------ 1 oracle oinstall 64 Oct 12 23:29 3 -> /dev/null
l-wx------ 1 oracle oinstall 64 Oct 12 23:29 2 -> /dev/null
l-wx------ 1 oracle oinstall 64 Oct 12 23:29 1 -> /dev/null
lr-x------ 1 oracle oinstall 64 Oct 12 23:29 0 -> /dev/null
lrwx------ 1 oracle oinstall 64 Oct 12 23:29 9 -> /u01/app/oracle/product/11.2.0/dbhome_1/dbs/hc_ORA11GR2.dat
lr-x------ 1 oracle oinstall 64 Oct 12 23:29 8 -> /dev/zero
lr-x------ 1 oracle oinstall 64 Oct 12 23:29 7 -> /proc/899/fd
lrwx------ 1 oracle oinstall 64 Oct 12 23:29 264 -> /u01/app/oracle/oradata/ORA11GR2/test.dbf (deleted)
lrwx------ 1 oracle oinstall 64 Oct 12 23:29 263 -> /u01/app/oracle/oradata/ORA11GR2/temp01.dbf
lrwx------ 1 oracle oinstall 64 Oct 12 23:29 262 -> /u01/app/oracle/oradata/ORA11GR2/example01.dbf
lrwx------ 1 oracle oinstall 64 Oct 12 23:29 261 -> /u01/app/oracle/oradata/ORA11GR2/users01.dbf
lrwx------ 1 oracle oinstall 64 Oct 12 23:29 260 -> /u01/app/oracle/oradata/ORA11GR2/undotbs01.dbf
lrwx------ 1 oracle oinstall 64 Oct 12 23:29 259 -> /u01/app/oracle/oradata/ORA11GR2/sysaux01.dbf
lrwx------ 1 oracle oinstall 64 Oct 12 23:29 258 -> /u01/app/oracle/oradata/ORA11GR2/system01.dbf
lrwx------ 1 oracle oinstall 64 Oct 12 23:29 257 -> /u01/app/oracle/oradata/ORA11GR2/control02.ctl
lrwx------ 1 oracle oinstall 64 Oct 12 23:29 256 -> /u01/app/oracle/oradata/ORA11GR2/control01.ctl
lr-x------ 1 oracle oinstall 64 Oct 12 23:29 11 -> /u01/app/oracle/product/11.2.0/dbhome_1/rdbms/mesg/oraus.msb
lrwx------ 1 oracle oinstall 64 Oct 12 23:29 10 -> /u01/app/oracle/product/11.2.0/dbhome_1/dbs/lkORA11GR2
[oracle@wang ~]$
8：将找到的句柄拷贝回来
[oracle@wang ~]$ cp /proc//899/fd/264 /u01/app/oracle/oradata/ORA11GR2/test.dbf
9：查看数据文件的状态
SYS@ORA11GR2>select file#,status,name from v$datafile;
FILE# STATUS NAME
1 SYSTEM /u01/app/oracle/oradata/ORA11GR2/system01.dbf
2 ONLINE /u01/app/oracle/oradata/ORA11GR2/sysaux01.dbf
3 ONLINE /u01/app/oracle/oradata/ORA11GR2/undotbs01.dbf
4 ONLINE /u01/app/oracle/oradata/ORA11GR2/users01.dbf
5 ONLINE /u01/app/oracle/oradata/ORA11GR2/example01.dbf
6 ONLINE /u01/app/oracle/oradata/ORA11GR2/test.dbf
6 rows selected.
10：将6号数据文件offline
SYS@ORA11GR2>alter database datafile 6 offline;
Database altered.
——再次查看数据文件状态：
SYS@ORA11GR2>select file#,status,name from v$datafile;
FILE# STATUSNAME
--------------------------------------------------------------------------------
1 SYSTEM /u01/app/oracle/oradata/ORA11GR2/system01.dbf
2 ONLINE /u01/app/oracle/oradata/ORA11GR2/sysaux01.dbf
3 ONLINE /u01/app/oracle/oradata/ORA11GR2/undotbs01.dbf
4 ONLINE /u01/app/oracle/oradata/ORA11GR2/users01.dbf
5 ONLINE /u01/app/oracle/oradata/ORA11GR2/example01.dbf
6 RECOVER /u01/app/oracle/oradata/ORA11GR2/test.dbf
6 rows selected.
11：恢复数据文件
SYS@ORA11GR2>recover datafile 6;
Media recovery complete.
SYS@ORA11GR2>
12：将6号数据文件online
SYS@ORA11GR2>alter database datafile 6 online;
Database altered.
13.验证：（文件已经修复回来了）
SYS@ORA11GR2>!ls /u01/app/oracle/oradata/ORA11GR2/test.dbf
/u01/app/oracle/oradata/ORA11GR2/test.dbf