Something wrong here, if your boss really know about DBA work, he will know that for every exam you will need hand on experience for 1-2 year.

This may be his excuse and may drive you to desperate action.

Better check with your DBA team whether they have any certification.

If your DBA team willing to bring you to the team ask them to show you or let them train you may be at lunch time.

The other way is go for Training, ask your boss if it is possible to send you for training.

By my experience reading from book has a slim chance to pass the exam (may be only me).

Exam prep like Selftest and Transender will do better but nothing can replace microsoft training at some training center.

Sometime all are not possible, I always wait for second shot which may come in August or near end of the year.

But absolutely I will have SQL server XXXX developer edition on my computer at work/home even I work as DBA.

IMHO, reading from web search for concern topic is much better than reading from book.

Nearly forget, safaribooksonline, cbtnuggets .. has video training for this topic at low cost or free for 7 days.

Good luck.

JJ