public object Evaluate(AvgFunction funcExp, object data, IEnumerable <object> parameters = null)
        {
            var paramValues = _GetParameterValues(funcExp, data, parameters);

            return(((IEnumerable <object>)paramValues[0]).Average(i => (decimal)i));
        }
 public string ToSQL(AvgFunction funcExp)
 {
     return(_FunctionToSQL(funcExp, "AVG"));
 }