RHCSA or RHCE certification ...
 

First thing is that what's your purpose of doing RH certification? Since you're working as a Database admin and both these certifications are typically intended for Linux system administrator. However, it all depends upon what Linux/system admin skills you already have. If you've good prior knowledge of managing Linux systems, then you better go with RHCE. Otherwise, as a beginner, you should go with RHCSA.

A little googling will shed more light on the difference between these certifications. IMO, RHCSA is intended to be the more basic Red Hat certification, whereas RHCE is for those who are little advanced in the field of System administration.

Just check it out:
http://www.redhat.com/training/certifications/rhce/
http://www.redhat.com/training/certifications/rhcsa/

This tidbit from the description of the RHCE should shed some light:

The prerequisites for the RHCE include the RHCSA. You can do the training at the same time, and you can even take the RHCE exam before the RHCSA, but you will not be awarded the RHCE until you've also earned the RHCSA.

You don’t have to get neither RHCSA nor RHCE.

But for whatever reason if you have to get certified, then, as you have mentioned - you are DBA and your main expertise is database, RHCSA is sufficient to manage linux where the database is installed.

And if you also happen/desire to maintain Linux's other server roles, for example, as goals set by Redhat for RHCE, then you can do it (RHCE exam).

• Configuring static routes, packet filtering, and network address translation.
• Setting kernel runtime parameters.
• Configuring an Internet Small Computer System Interface (iSCSI) initiator.
• Producing and delivering reports on system utilization.
• Using shell scripting to automate system maintenance tasks.
• Configuring system logging, including remote logging.
• Configuring a system to provide networking services, including HTTP/HTTPS, File Transfer Protocol (FTP), network file system (NFS), server message block (SMB), Simple Mail Transfer Protocol (SMTP), secure shell (SSH) and Network Time Protocol (NTP).

Having knowledge outside your area of expertise is always a good thing.

If your main area of expertise is (oracle) DBA and you are working on Unix/Linux based platforms then having a solid knowledge about Unix/Linux is a good thing.

I'm not sure if you need to be certified when it comes to "outside expertise". There are other, cheaper ways to get this knowledge.

If I assume for the moment that you (or your [future] boss) value certifications, I would advise the following: Get RHCSA certified and forget about RHCE for the moment.

As stated before in this thread: You need to be RHCSA certified before you can get RHCE certified. RHCSA is valid for 3 years. If you do find out that the in-depth knowledge that RHCE provides is actually needed you can take this certification at a later date.