The Data - how to?

[l.v.p]

As a programmer I always get stuck at the same moment: handling the data. I'm not talking only about Qt (and/or C++) but as wide as the topic is, how to handle the data in your program, and which type of these choose?
When should I use databases, when raw binary file format, when XML? Maybe txt files are way better than db in come cases?
How you earned the knowledge of handling the data? Courses? Books? Your own apps?
Can you recommend me some titles which will enlighten me on this topic?

[andre]

There is no One True Answer(TM) here. Unfortunately, the answer is always: it depends. It depends on what formats you need to be able to read and write to communicate with other applications. It depends on the size of your data store. It depends on the type of access you need to your data, like do you need it all at once, or do you only need small pieces at a time? What types of querying for the data do you need to support? How flexible does it need to be?

The right answer comes from experience, and to be honest, from personal preference as well.

[dunix]

For me, my opinion is that the database gives you much more easily when then use that data. Perhaps it is that I feel confident in mysql and then we can do things with, but it all depends on what you do at the end, like said Andre in the previous post.