Leaderboard

__DIR__ is a "magic constant" (it's a constant with a value that varies) that is the directory of the file you put that code in. That's all there is to it. Period. Super simple. Nothing to do with URLs. Nothing to do with MVC design. Nothing to do with your website, really. Just a directory path.

I'm not going to spend time writing SQL that I don't believe should be written in the first place, but if you insist on pursing this, I'll at least give you a hint. CASE

You won't learn anything useful about SQL pursuing this design because the design is fundamentally flawed and directly opposed what SQL is designed to do. My answer is that you don't. I'm sure there is a way for it to be done, but doing so would teach you nothing useful. The correct solution to your problem is to re-design your table structure, then use SQL as it's intended to be used rather than fight against it trying to make a poor design work. This shows yet another potential reason why your design is flawed. Why do you have multiple rows for the same link? If the answer is "To have more than 4 key words" then that's wrong. The multi-table solution gives you the ability to have an unlimited number of keywords per link.