Command Line Tools in Oracle 10g and 11g

In 10g, if we did not include a connect argument on the command line, the command would take the value of the environment variable ORACLE_SID by default.

In 11g Release,we must use the connect argument to specify the database. Oracle Internet Directory and Oracle Database are not installed in the same ORACLE_HOME, so ORACLE_SID is irrelevant. Therefore, we must use the connect argument to specify the database, for example connect=oiddb.