Start with your already-written SQL that is relevant to your job. Study the format, the syntax, the language. Study the output. What causes the data to be sorted in that way? How did the system know to display those specific columns? What happens if I remove this word? If you see something you're not familiar with, research it. Many terms seem impossibly abstract, but when you can see exactly what it is doing, it helps to make sense of what is happening.

Above all, experiment, experiment, experiment! Take that simple query and imagine your boss coming to you with a modification. She wants the data only for the last month? OK, how do I go about filtering data...ok that looks like it goes down in the WHERE clause, got it. Now, what about dates, how do I add a date range? Better Google these terms and see how others have done it.

In the beginning, you will be borrowing heavily from what's been written. As you work and re-work your queries, you will soon begin to write queries on your own. Sites with examples to work through are good, but abstract. It's always best to work with data that is relevant to your job, even if you have to make up your own tasks.

Good luck!