Trick #1 - Copying Users the Right Way

Today’s trick is pretty simple, and it allows you to copy user accounts from one instance to another with the same password, grants, roles, etc, without using the exp/imp tools.

Everyone knows that you can use “create user username identified by password” to create a new user. What most people don’t know is that you can actually copy the password of a user from one database to another as well.

You wont be able to see the password (sorry hackers), but you can copy it in its encoded form.

Instead of using:

create user test identified by password;

You will use:

create user test identified by values 'encoded password';

The encoded password will actually be the encrypted password stored in the database that is visible to the DBA eye. This is a 16 character password you will find in the DBA_USERS view in the PASSWORD column.

You can also use:

alter user test identified by values 'encoded password';

If you have already created the user and need to change the password to what it might have been on another system.

This is extremely useful for DBAs that are copying their production database to development, or migrating a database from one instance to another. Too often, DBAs are forced to remember the details they have, copy them from the DBA_USERS view, and try to create the new users as close as possible to the original.

But we’re more sophisticated! Instead, we will use the DBMS_METADATA package to pull the user information.

set head off
set pages 0
set long 9999999
select dbms_metadata.get_ddl('USER', username) || '/' usercreate
from dba_users;

USERCREATE
--------------------------------------------------------------

CREATE USER "SYS" IDENTIFIED BY VALUES 'F894844C34402B67'
DEFAULT TABLESPACE "SYSTEM" TEMPORARY TABLESPACE "TEMP"
/

...

Do you want to get all their roles and grants as well? Nothing easier! Look at the following:

SELECT DBMS_METADATA.GET_GRANTED_DDL('ROLE_GRANT','SYS') FROM DUAL;
SELECT DBMS_METADATA.GET_GRANTED_DDL('SYSTEM_GRANT','SYS') FROM DUAL;
SELECT DBMS_METADATA.GET_GRANTED_DDL('OBJECT_GRANT','SYS') FROM DUAL;

From this, we can form our Unified User Copy-o-matic with the following query:

set head off
set pages 0
set long 9999999
spool user_script.sql
SELECT DBMS_METADATA.GET_DDL('USER', USERNAME) || '/' DDL
FROM DBA_USERS
UNION ALL
SELECT DBMS_METADATA.GET_GRANTED_DDL('ROLE_GRANT', USERNAME) || '/' DDL
FROM DBA_USERS
UNION ALL
SELECT DBMS_METADATA.GET_GRANTED_DDL('SYSTEM_GRANT', USERNAME) || '/' DDL
FROM DBA_USERS
UNION ALL
SELECT DBMS_METADATA.GET_GRANTED_DDL('OBJECT_GRANT', USERNAME) || '/' DDL
FROM DBA_USERS;
spool off;

And voila! All of our users and grants all in one simple script.

If you would like simple alter commands instead, we can always skip using DBMS_METADATA. Instead, use this query:

select 'alter user ' || username ||
' identified by values ''' || password || ''';'
from dba_users;

Note that in the case above, there are three single quotes to the left and right of password. Don’t use double quotes.

That’s it for today; a rather easy trick that you can use many times during your DBA career. If you already knew this trick, don’t worry! There’s more to come, the rest a bit more advanced and a bit more obscure. Join me tomorrow and we’ll talk about how to transform any query into any other on the back-end, sometimes with very amusing results!

Ref : http://www.oraclealchemist.com/news/trick-1-copying-users-the-right-way/