Is there some kind of simple database system that uses simple text or xml files for data storage? I just need some basic functionality like update,delete, insert, simple constraints and relations.
For the project that I have now using SQL Server would be too heavyweight and I have never really liked it anyway.
Yes it is: SQLite 🙂
There is ADO Provider:
http://sqlite.phxsoftware.com/forums/default.aspx?GroupID=2
There is article on that:
http://www.aspfree.com/c/a/Database/Using-SQLite-for-Simple-Database-Storage/