Tips 2 (Question 2)

Your Oracle server has four databases SALESDB, FINDB, HRDB, and TESTDB installed on it. The SALESDB database is currently running. You set the ORACLE_SID environment variable on the operating system as follows:
C:\> SET ORACLE_SID=TESTDB

Then, you try to start the TESTDB database from another SQL*Plus prompt using this command:

SQL> STARTUP;


What will be the result of this command?

• The command will start the TESTDB database without any alterations to the SALESDB database.

• The command will start the TESTDB database and shut down the already-running SALESDB database.

• This command will return an Oracle already running, shut it down first error.

• The command will not start the TESTDB database because the assignment of the ORACLE_SID environment variable is incorrect, and you must specify the specific parameter file when issuing the STARTUP command.
  

Explanation:
The command will start the TESTDB database without any alterations to the SALESDB database. Setting the ORACLE_SID environment variable specifies the instance name for the database that is to be started. In this scenario, because there are four
databases on the same server you should specify the instance name that is to be started using the ORACLE_SID environment
variable. Setting this variable will not affect the instances that are already up and running.

The option stating that the command will start the TESTDB database and shut down the already-running SALESDB instance is
incorrect because the SALESDB instance will not shut down as a result of the STARTUP command.

The option stating that the command will return an error is incorrect because the error is generated only if you have not specified the instance name by setting the ORACLE_SID environment variable. If this variable is specified, this error will not be
generated.

The option stating that the command will not start the TESTDB database because the assignment of the ORACLE_SID variable is incorrect because the variable is set appropriately in this scenario. Additionally, it is not necessary to specify the specific
parameter file when issuing the STARTUP command. If no parameter file is specified, the default SPFILE will be used, if the SPFILE is not available, the default PFILE will be used to start the database.