Okay so this happened ages ago (nearly five years) but this suddenly came to my mind again.

It was in the first year of my study (currently in my 5th and last year).

I was experimenting around with php and mysql during some free hours. All the insert,delete and so on statements worked perfectly find except for one update statement. Started to debug of course and after a little while of no results I was like "oh yeah right, something like logs exists of course". Looked in the logs but nothing. No matter how I altered my code (rewrote it numerous times for some 'clean starts') it just would not run the update statement.

Alright, time for some class mate help. After multiple hours of debugging with a few classmates, there was still no result at all.

Time to bring in one or more teachers. After hours of debugging, still no result even with the help of a few good teachers.

Decided to give it a rest for that day.

Two weeks later it still was not updating anything/working and I finally gave up.

Till today, I still have no clue what went wrong and it still bugs me from time to time :/