Error Handling When Using Dictionary
In your data structure include a validator (this should probably be a Predicate&lt;String&gt;); most of the predicates will just return true, but the two that require integers will have a nontrivial validator that checks for integer.

So I guess the type should be Dictionary&lt;String, Tuple&lt;Func&lt;SqlConnection, String, DataSet&gt;&gt;,Predicate&lt;String&gt;&gt;