Oracle system identifier(SID) "xxx" alread exits. Specify another SID

案例环境：

               操作系统    ：Oracle Linux Server release 5.7 64 bit

               数据库版本：Oracle Database 10g Release 10.2.0.4.0 - 64bit Production

案例介绍：
在一个刚刚安装实例的服务器，使用dbca创建新的数据库时，在指定全局数据库名（Global Database
Name）后，点击下一步时。报如下错误：The Oracle system identifier(SID) "SCM2" alread
exits. Specify another SID

出现这个错误，是因为在/etc
/oratab文件中已经指定了$ORACLE_SID（上次删除数据库时，没有彻底清除/etc/oratab），此时只需要将SCM2:/u01
/app/oracle/product/10.2.0/db_1:N 这一行删除或注释即可。

[root@DB-Server ~]# more /etc/oratab

#

# This file is used by ORACLE utilities. It is created by root.sh

# and updated by the Database Configuration Assistant when creating

# a database.

# A colon, ':', is used as the field terminator. A new line terminates

# the entry. Lines beginning with a pound sign, '#', are comments.

#

# Entries are of the form:

# $ORACLE_SID:$ORACLE_HOME:<N|Y>:

#

# The first and second fields are the system identifier and home

# directory of the database respectively. The third filed indicates

# to the dbstart utility that the database should , "Y", or should not,

# "N", be brought up at system boot time.

#

# Multiple entries with the same $ORACLE_SID are not allowed.

#

#

SCM2:/u01/app/oracle/product/10.2.0/db_1:N