A small collection of my most used aliases.

===== Unix =====
==== Quickly get into a database ====
Set these in the .(bash_)profile of the oracle account
<code>
 alias dba='sqlplus / as sysdba'
</code>
This will only work if a database has already been selected using ". oraenv"\\
When I work out how to use multi-line in an alias, this can be made better with something like:
<code>
 alias dba='export ORAENV_ASK="NO";export ORACLE_SID="$1". oraenv;sqlplus / as sysdba'
</code>
Then it could be used like so
<code>
 dba dev02
</code>

==== Set the SQL prompt so you can see what database you are on ====
In the file $ORACLE_HOME/sqlplus/admin/glogin.sql, put:
<code>
 set sqlprompt "_USER'@'_CONNECT_IDENTIFIER _PRIVILEGE> "
</code>
Might be useful to add some other often used settings:
<code>
 set linesize 200
 set pagesize 200
</code>
Very useful as of 10g is that this file is re-read after a connect from inside SQL*Plus

There is also a login.sql file that will be read (if it exists) which can either be in the current directory or in an environment variable $SQLPATH

===== Windows =====
==== Quickly get into a database ====
Create a file dba.bat that contains:
<code>
 @echo off
 set ORACLE_SID=%1
 sqlplus / as sysdba
</code>
Then this file will either have to be put somewhere on the %PATH%, the %PATH% modified to include the script dir or cd to the script dir before calling it.