Many application development environments provide direct SQL access to Oracle databases. The SQL commands shown in this module will work from within those tools, but the commands specific to
SQL*Plus (such as describe) will not.
If the command fails, there are several potential reasons: Oracle is not in your path, you are not authorized to use SQL*Plus, or Oracle has not been installed properly on your computer.
If you get the message
ERROR: ORA-1017: invalid username/password; logon denied
either you have entered the username or password incorrectly or your username has not yet been set up properly on your copy of Oracle.
After three unsuccessful attempts to enter a username and password that Oracle recognizes, SQL*Plus will terminate the attempt to log on, showing this message:
unable to CONNECT to ORACLE after 3 attempts, exiting SQL*Plus
If you get this message, contact the database administrator of your company.
Assuming everything is in order, and the SQL> prompt has appeared, you may now begin working with SQL*Plus. When you want to quit working and leave SQL*Plus, type this: