You can't communicate directly with SQL from Angular. You are going to need a server side language to act as a middle man. The choice of which language really depends on what you have experience with. Assuming you are referring to Microsoft's SQL Server, a language like C# offers first class support but I fear the learning curve would be too high if you don't already have experience with it. Since you do know JavaScript, you can try something like NodeJS for your backend and use an npm package like tedious to connect.

Does it have to be SQL? You can try something like firebase which is a "backend as a service" meaning you can create your angular apps and write/retrieve information from a database securely. Whats more, one connects directly to it without needing to deal with writing up a bespoke API. There's even a angular module for it. I would recommend going this route if you are uncomfortable with the first approach.

Your best bet is to build some APIs to interact with the SQL Server. You could use any runtime to do that -- WCF, WebAPI (since you're talking of SQL Server, I guess you're on a Microsoft stack), PHP (it should have a SQL Server connector) or whatever you want.

Writing this, this morning so it's not quite finished (needs input sanitization, mysql converted to mysqli, etc...) but I think it's a decent example of using PHP / MySQL mixed with AngularJS 1.x to read in comments and submit comments and refreshing the comments list without refreshing the page - for a very simple 2 page blog system (they hate wordpress / wanted something custom)

http://pastebin.com/Wp22fjAp