There are two common approaches. First, you can pass System.Type
object GetColumnValue(string columnName, Type type)
{
// Here, you can check specific types, as needed:
if (type == typeof(int)) { // ...
This would be called like: int val = (int)GetColumnValue(columnName, typeof(int));
The other option would be to use generics:
T GetColumnValue<T>(string columnName)
{
// If you need the type, you can use typeof(T)...
This has the advantage of avoiding the boxing and providing some type safety, and would be called like: int val = GetColumnValue<int>(columnName);