Well, you can, but using a database will give you more specific, organized, and reliable information.
Databases are organized collections of subject specific information. The information in a database is usually published in other places (like magazines and books) so it is more likely to be credible (meaning that it's TRUE!). All of the links above are to databases.
Google is a search engine. Search engines are not organized in any way and bring up information from the entire internet. The information that is retrieved by a search engine can be anything - articles, opinions, etc. It doesn't mean that you won't find good info on Google, but there's is no guarantee that you will, either. You'll just have to work a little harder to make sure the information you're finding is correct. A good way to do this is to make sure your information has the following:
An author
A current date (some exceptions)
Correct grammar and spelling
Cited sources or a bibliography
And you should always compare your information to another source (or two) to make sure they say the same thing. Does one source say the sky is blue and the other says the sky is orange? It probably means you should find another source to verify which one is the correct answer!