Text File Use As Database

Mart is right. Text files are not fit for such a use. Mostly they are use for reading & grabing data from them and not to write to it. This is a very resource consuming and difficult task. I mean, you can do it, but there are better ways. Much better.
Because it's so difficult, I'm afraid nobody would have enough time to device some sample code for you. If you realy want, you have to figure yourself.