ionic tutorial - You can't do it directly from Ionic framework in Ionicframework - ionic framework - ionic 2 - ionic creator - ionic development
The thing is; you can't connect Ionic to any database (MySQL, Postgres, MSSQL, ...) directly. The keyword here is directly. No, there's no workaround, no magic involved, it's just not the way this is supposed to work. Ionic works on top of Angular and Angular is a frontend framework. However, the way you should do it is that you basically create a (RESTful) API on your server side. Most likely this will be made with some serverside language (PHP, Go, Python, ...) which will talk directly to your database and query it. After you write your (RESTful) API you can consume it through your services in Angular by using Angular's $resource or $http service.
Example
Consuming Giphy API with Angular's $http service:
var search = 'cats';
var link = 'http://api.giphy.com/v1/gifs/search?api_key=dc6zaTOxFJmzC&q=' + search;
$http.get(link).then(function(result){
console.log(result);
});