Databases have always been tough for me.  SQL joins are very difficult to process and remember.  Here are a couple of articles that I always reference when trying to re-understand the process of joins:

Visual Explanation of Joins

Visual SQL Joins

Ran across a great series of posts from an Oracle DBA who was forced by his work to take up MySQL. He describes some interesting similarities and differences between the two. part 1, part 2, part 3, and part 4.

I was called out today to an emergency at a client’s site about 3 hours drive away. Their database server was down. Arms, I was told, were flailing about. Other than that, I had no details. When I got onsite, I was escorted into the server/boiler room in which was a behemoth that would easily crush my SUV. Attached to it was a crummy little terminal that was lucky not to spray sparks when powered on, although it did seem hesitant to do anything with those electrons.

It turned out to be an ancient HP-UX box running an arcane SQL database of some sort. It wouldn’t boot until I coaxed it, and I could never encourage it to mount the important filesystems. The terminal screen was very faint and was miserably hard to read and had a tendency to scroll too quickly (at 300 baud, probably) for me to make sense of, so I pulled out my digital camera and snapped shots of the screen as it was easier to read on my inch and a quarter LCD. Here’s a sample:

I didn’t notice until later the date on that screenshot. October 26, 1994. Important data, some called it “mission critical,” on a box that was at least 11 years old and, I’m certain, has no clue what a patch is. There was a tape drive attached to the dinosaur, complete with a stack of tapes on top. I doubt that the drive had been able to move in years, so I knew not to waste my breath asking “may I peruse your business contunity plan?” Anyway, it was just sad to see them lose important data because of… cheapness? Stubborness? Ignorance? I bet the electric bill for that bad boy in a year would buy a really nice AMD-based server with the OS of their choice and a MySQL install that would run isododecahedrons around that thing. I tried to get a picture of the thing itself, but I couldn’t get far enough away from it in that nasty storage room. Sad.