I have been struggling for a similar problem. But my problem is that "my preference" is not a single piece of data, but a list, a preference list that consists of N elements. Image that I build a list of my favourite songs, which allows me to list top N songs as No 1, No 2 until No N. How do I design my database? I get suggestions that either object is used or the preference list to be comma separated strings. But I am not satisfied with either, any good suggestions? Oh, I am not happy with object because of its complexity of data maneuverability.