/// <summary>
        /// 执行linqDLR2Sql的where操作
        /// </summary>
        /// <typeparam name="TSource"></typeparam>
        /// <param name="source"></param>
        /// <param name="predicate"></param>
        /// <returns></returns>
        public static LinqDLR2Sql <TSource> Where <TSource>(this LinqDLR2Sql <TSource> source, Func <TSource, LinqDLR2SqlWhereOperator> predicate)
        {
            LinqDLR2SqlWhereOperator op = predicate.Invoke(source.Item);

            source.DoWhere(op);
            return(source);
        }