Well, the error you are getting is that you have two different types of commands and you can't just set one to the other.
I really haven't used an OracleCommand before, but after reading the
MSDN[
^] on it....it doesn't look like it can do a FILL. It looks like it only has capabilities of reading one line at a time with a reader, or doing scalar or non query operations.
Also, I know you say you are using VS 2005, but the .NET Framework 4 says this API is now obsolete. So it's not something that you will ever be able to upgrade to in the next versions of Visual Studio....if you ever take this project and upgrade it.
So...My suggestion is to connection to the Oracle Database with a different provider.
Here[
^] is a tutorial on how to link to oracle using an ole db provider. The ole db provider has the ability to perform a fill operation.
And
here[
^] is a list of other ways you can connect.