GetValue

public static class DataReaderExtension
{
    public static string GetValue(this IDataReader rdr, string columnName)
    {
        return rdr.GetValue<string>(columnName);
    }

    public static T GetValue<T>(this IDataReader rdr, string columnName)
    {
        object data = rdr.GetValue(rdr.GetOrdinal(columnName));
        if (!string.IsNullOrEmpty(data.ToString()))
            return (T)data;

        return default(T);
    }
}

var value = rdr.GetValue<string>(columnName);
var value = rdr.GetValue(columnName);
var value = rdr.GetValue<int>(columnName);
var value = rdr.GetValue<int?>(columnName);