Basically it comes down to the difference between .Net 2.0 (2005) and .Net 3.5 (2008) Framework. Basically what you code in .Net 2.0 won't work the same if at all with .Net 3.5 framework. But ...

The reason it is Null is this :


dsExcel.Clear();

You are clearing the Dataset, i.e. making it empty, and then updating it. That is why it would read NULL

Example of SQLCommandBuilder

I have a few times. It can depend on many things, but often it depends on the how you setup your SQL scripts.

Here is a pretty good reference Dani

C# Corner (http://www.c-sharpcorner.com/language.asp)