a new dba should be really good in sql . do lot of sql exercises and you will become very good in sql and will grow in your career.
if you dont have oracle installed on your machine , dont worry. you can do them online.
go to this link
http://apex.oracle.com/i/index.html
and create a new account for yourself ..your account login and password will be sent to you and using that you can log in and practice your sql statements online.
after you log in you will see a screen similar to the following..if you dont know which table name to enter click on the torchlight icon on the screen and it will show you the list of available tables..
you can read the importance of knowing sql by reading this article
