How do I connect a sql server to my Javascript game?

I'm working on a project and I just need a holistic overview on how to go about it.

I'm going to use HTML/CSS canvas to make the game.

However, the game involves visualization of large amounts of data that is best served in a database. What I do not know how to do is: 1) Link my HTML/CSS game to a SQL database 2) Parse a text file to populate the database.

I don't have specific issues I just don't even know where to start? Some people have said AJAX? Others have said parse.com?