ORACLE_SID環境變數設定的問題

明明在登錄檔裡存在環境變數ORACLE_SID的設定，可執行emctl時卻提示：

C:>emctl
Environment variable ORACLE_SID not defined. Please define it.

C:>

在系統環境變數增加ORACLE_SID的設定之後可以解決這個問題。

[@more@]

在系統環境變數增加ORACLE_SID的設定之後再次執行emctl發現不會出現提示：Environment variable ORACLE_SID not defined. Please define it

印象中記得asmcmd也有這樣的問題（記不太清楚了），oracle的有些命令為什麼不去登錄檔中讀取oracle_sid?

C:>emctl start dbconsoe
Oracle Enterprise Manager 10g Database Control Release 10.2.0.1.0
Copyright (c) 1996, 2005 Oracle Corporation. All rights reserved.
Invalid arguments

Unknown command option start
Usage::
Oracle Enterprise Manager 10g Database Control commands:
emctl start| stop| status| setpasswd dbconsole
emctl secure

emctl set ssl test|off|on em
emctl set ldap
emctl blackout options can be listed by typing "emctl blackout"
emctl config options can be listed by typing "emctl config"
emctl secure options can be listed by typing "emctl secure"
emctl ilint options can be listed by typing "emctl ilint"
emctl deploy options can be listed by typing "emctl deploy"

C:>emctl start dbconsole
Oracle Enterprise Manager 10g Database Control Release 10.2.0.1.0
Copyright (c) 1996, 2005 Oracle Corporation. All rights reserved.

Starting Oracle Enterprise Manager 10g Database Control ...OracleDBConsoleorcl
服務正在啟動 ...
OracleDBConsoleorcl 服務已經啟動成功。

C:>