I'm relatively new to BI / Data visualisation and I'm looking for sites which I can use to help learn both topics i.e. how to you take RAW data and eventually get it into a format and model which make data analysis easier. More importantly I'm looking for communities where you can ask questions about the topics, similar to this one but which have a broader focus on all BI rather than just tableau.
I am familiar with MySQL and also PowerPivot, but I'm now trying to learn the best ways of taking my data from a fairly complicated MySQL database (lots of databases, each with lots of tables) so that I can use the data in various BI / Dashboard applications - we want to use interactive dashboards throughout the company to make data more accessible. I've tried using just direct SQL queries but often these are too slow so I believe there must be an approach to flattening the MySQL data before querying it but I am unfamiliar with this. This is the kind of learning I'm trying to accomplish.