You're not really supposed to be seeing this.. site is a work in progress.. but feel free to bookmark lert.us and come back later!
Or at least hire someone to write it for you.
SQL is how you interact with data.
Data answers questions.
So if you want to be able to answer questions, you'll need to look at data, and SQL will help you do that.
Of course you may have some reporting at your disposal, but what happens if you want to know some metric that isn't in any report.
For example, maybe I'm curious to know (roughly) the average number of words in the blog posts on this site and that doesn't happen to exist in any report?
SELECT AVG(LEN(content) - LEN(REPLACE(content, ' ', ''))) FROM posts
Well to be honest, there are some flaws with that so it's not 100%, but it does give a rough idea.
How can I learn SQL?
There are a ton of resources out there, but the best way will be to practice. Think of different ways you'd like to look at data and figure out how to write a query to do that.
I've been working with SQL Server for the last 12 years and have found it to be a marvelous data platform. I love writing SQL and sharing my knowledge.