The only way that i know of is to test for it, you can do a combined if though to make it easy.
If NOT IsDbNull(myItem("sID")) AndAlso myItem("sID") = sId Then
'Do success
ELSE
'Failure
End If
I wrote in VB as that is what it looks like you need, even though you mixed languages.
Edit
Cleaned up to use IsDbNull to make it more readable