Comment by mamcx

Well I have, related to databases.

I was the developer of one of the most used app for managing schools in my country (think: scores, grades, students, etc)

In my country, this look like this: (Ugly as hell, but that is not the one I design for the app)

http://www.slideshare.net/wildercondori/planilla-de-califica...

At first, the database was normalized. You have the obvious relations where of students, periods, class/grade, etc... so was a tree.

At the time of editing and printing (this was circa 2000 with FoxPro) things get complicated... fast (was important that editing the scores for each students be very fast).

It was my first serious job, and I'm a self-taught developer, so I don't know back them that my tables were a tree, neither any data-structure apart from the used in Fox.

But one day it hit me: Why I'm doing the tables this way? I see the pice of paper that show how manually a teacher do the scores, and I think: I will do the tables EXACTLY LIKE THIS (ie: As you see in the image above).

Suddenly, everything else get easy. Printing was easy. Editing was fast. Less errors. The app was a hit in part for that "small" change. Look like the competitors never get that idea back them.