Came here to say the same thing. Some years back, to pass my CS databases course, we were required to write really complex queries in the computer lab. We had v

Came here to say the same thing. Some years back, to pass my CS databases course, we were required to write really complex queries in the computer lab. We had very limited time to do so. Many people failed because their queries became complex monoliths, hard to debug or optimize when things went wrong. That's because they limited themselves to SQL-92. We were using Oracle, so there was no reason not to use SQL:1999. I made heavy use of WITH, and it was quite effortless.