Option gray when dbca deletes a database

In this case, you have previously copied and restored all files under/u01/app/Oracle. to delete an existing database, it is found that the delete database option in dbca is gray. But there is actually a database, so I suspect that the configuration file does not match. After reading some information on the Internet, you can directly modify/etc/oratab. After the actual operation, you can:

The original content in/etc/oratab is as follows:

$ Cat/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 shocould, "Y", or shocould not,
# "N", be brought up at system boot time.
#
# Multiple entries with the same $ ORACLE_SID are not allowed.
#
#
# *:/U01/app/oracle/product/9.2: N
# *:/U01/app/oracle/product/9.2: N
# *:/U01/app/oracle/product/9.2: N
# *:/U01/app/oracle/product/9.2: N
# *:/U01/app/oracle/product/9.2: N
# *:/U01/app/oracle/product/9.2: N
# *:/U01/app/oracle/product/9.2: N
*:/U01/app/oracle/product/9.2: N

You only need to change the * in front of the last line to the ORACLE_SID you want to delete.