public static async Task <T> MaxAsync <T>(this QueryFactory db, Query query, string column)
 {
     return(await db.AggregateAsync <T>(query, "max", column));
 }
 public static async Task<T> SumAsync<T>(this QueryFactory db, Query query, string column)
 {
     return await db.AggregateAsync<T>(query, "sum", column);
 }