Database choice and data architecture exclusively depend on details of your project including data level, number of users, layers and tiers. If your dataset is very huge it is possible you need NoSQL solutions. MySQL versus Oracle DB have less functionality but it is easy and free. If functionality of MySQL is enough for your project that it is better to use MySQL.
Dimitry is right! MySQL is free and should be able to handle your huge dataset.
If you are not familiar with programming/database programming, MySQL can be managed nicely with the graphical interface phpMyAdmin (which is also free and available on all platforms).
Truly MySQL would be my choice in nearly all my applications. Especially when it is coupled with WampServer, XAMPP or MAMP.
I tried Oracle SQL before and in my opinion it took up more resources and caused my computer to slow down. It may be because it was a netbook back then with 1-GB RAM, Intel Atom processor. However, my point is that a MySQL server on the same computer worked without any worries. Not to mention I used the same computer to process the whole of the GPDS 960 Signature Corpus database and processed data of over 5000 students in the same MySQL application.