Claudio,
To the best of my knowledge, in ASP 1.x, the textbox control doesn't have a DataSource property.
Only way I can immediately come up with would be to load the initial value and set the text based on a database field, and then save the edited value from the Textchanged event back to the database.
I'll do a search on here to see if there's any other way (because I'm curious now). Maybe someone else on here has done it and has a better way.
Kevin