Three steps are involved

1. Start an instance.
2. Mount the database.
3. Open the database

1. Log in as oracle (or any user in group dba)

2. Set your ORACLE_SID to the instance you want to start. Verify that your ORACLE_HOME is set to the correct database version

3. Start SQL*Plus and connect as sysdba

4. Start the database.

During database startup you can specify the state it will open to. The default is open(startup) but you can specify STARTUP NOMOUNT or STARTUP MOUNT depending on which task to perform.

c:/>SQLPLUS / AS SYSDBA

connect to an ideal instance

now we can start the database with any of the stage as the requirement.

SQL>STARTUP NOMOUNT

or

SQL>STARTUP MOUNT

or

SQL>STARTUP OPEN

Steps are

NOMOUNT STAGE

• SGA is allocated
• background processes are started
• Alert log file is opened

Mount Stage

• controlfiles is read
• name & location of the daatfiles logfiles are detected

Open Stage

• files are opened

In this way database gets opened. Hope you got clear picture. -- Aruna

Hi Aruna

Thank you...

Bye

Ragards

Ravinder

Hello Aruna

The way you have explained the process(steps) involved in database startup is excelent

Best Regards

Sanjay