Hi there,

I'm having some trouble! I am writing strings to a database varchar field that allows nulls but when I try to pass a string with the value of dbnull from a Data Row Field into the Data Sets update method it throws an invalid cast exception. I understand why but it just does not make sense to me in this context... The db field allows null so therefore the update method should allow it too. I understand String are not allowed to be nullable types. But something is missing here...

The DAL is a strongly typed dataset created using strong typed DataTable objects

Can anyone explain this to me (this also happens with numeric values) and/or suggest a solution for this.

Thanks for reading!

(A highly panicked Adam)

Ah, the wonders of null.  Try this assignment

DataField = string.IsNullOrEmpty(YourStringValue) ? DBNull.value : YourStringValue

ADO.NET doesn't understand null, but it does understand DBNull.