工作中经常用到的linq根据传入数据集合查询对应子级数据，整理共享，希望大家都能用得上，代码中doublesArray 为父节点对应ID数据集合，再根据ID数据集合查询全部子级数据。

            //获取缓存数据
            object obj = Caching.GetCache(CacheKey + UModel.RoleId);
            if (obj != null)//判读缓存数据是否null
            {
                SysFunList = (DataSet)obj;
            }
            else
            {

                string strSql = "select * from View_SysRoleList where LoginID='" + UModel.LoginId + "' order by [Custom_Displayorder]";
                SysFunList = SqlHelper.Query(SqlHelper.LocalSqlServer, strSql.ToString());
                Caching.SetCache(CacheKey + UModel.RoleId, SysFunList);
            }

            //linq获取数据集内所有父节点数据
            var query = (from t in SysFunList.Tables[0].AsEnumerable()
                         where t.Field<int>("Custom_ParentNodeId") == 0
                         select t);

            if (query.Count() > 0)
            {
                //linq获取数据内所有父节点对应ID
                var doublesArray = query.Select(one => one.Field<int>("Custom_NodeId"));
                if (doublesArray.Count() > 0)
                {
                    //linq 根据ID数据结合获取对应下一级数据
                    var foos = from tq in SysFunList.Tables[0].AsEnumerable()
                               where doublesArray.Contains(tq.Field<int>("Custom_ParentNodeId"))
                               orderby tq.Field<int>("Custom_Displayorder") descending
                               select tq;

                    //转换为DataTable
                    DataTable boundTable = foos.CopyToDataTable<DataRow>();
                    RepeaterMeau.DataSource = boundTable;
                    RepeaterMeau.DataBind();
                }
            }