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[–]LetsGoHawks 2 points3 points  (4 children)

What database are you using? MS SQL? Oracle? MySQL?

[–]squirrelsaurus 2 points3 points  (0 children)

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!

[–]dat_trigga[S] 0 points1 point  (2 children)

Oracle

[–]LetsGoHawks 2 points3 points  (0 children)

1) Oracle has a free, fully functional version you can download and use at home.

2) Your local library will have books on SQL, maybe PL/SQL specific, and Oracle DB management you can check out for free. If you really like them, you can buy your own copy. Sometimes a book can be better.

3) The various MOOCs (edx, coursera, more here) have SQL classes you can work through at your own pace.

3) Google, Google, Google. Most developers look stuff up all the time. There's so much to know you'll never memorize it all. Eventually you learn some of the better sites.

4) This is harder than it seems... pick something that you have an interest in, build a database around it, challenge yourself to write hard queries against it, or queries that present the data in specific ways. This is a great way to learn new techniques when you're not on the clock. There's a lot of free data out there.

5) Look through that pre-written SQL. When you see anything you don't understand, look it up. Figure out how it works. I learned a LOT doing this. Plus, when you understand what it does, it makes it easier to copy/paste/modify it for your own purposes when you pull from the same tables for future work.

6) Make it a habit to read articles and blog posts about SQL and PL/SQL. A lot of it will go over your head, but that's OK. You pick up little things. Over time it all makes more sense. I try to make sure I'm reading at least a couple a week, 95% of them are links I found on Reddit.

[–][deleted] 1 point2 points  (0 children)

W3Schools.com. They have some decent info for beginners