A database can be ordered via our support: https://support.99stack.com, all you have to do is to open a support ticket and ask for a MySQL database to be installed on your host. Please include your customer ID and the host name or IP in your ticket, otherwise you'll get a reply first asking for the same information and some information about where you can find your customer ID and host IP. The installation is manual and can take up to 48 hours to process, usually it's faster however.
The price for a MySQL database is $0.001/hour/GiB, the price will be rounded up to nearest GiB so 1-1000MiB is charged as 1GiB, 1001-2000MiB is charged as 2GB and so on. We won't put any restrictions about what you choose to store in your database but we would like to know if you intend to store large amounts of data like 10 GiB or more in order to scale our servers properly.