工作中经经常使用到的linq依据传入数据集合查询相应子级数据，整理共享，希望大家都能用得上，代码中doublesArray 为父节点相应ID数据集合，再依据ID数据集合查询所有子级数据。

            //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获取数据集内全部父节点数据

            var query = (from t in SysFunList.Tables[0].AsEnumerable()

                         where t.Field<int>("Custom_ParentNodeId") == 0

                         select t);

            if (query.Count() > 0)

            {

                //linq获取数据内全部父节点相应ID

                var doublesArray = query.Select(one => one.Field<int>("Custom_NodeId"));

                if (doublesArray.Count() > 0)

                {

                    //linq 依据ID数据结合获取相应下一级数据

                    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();

                }

            }