Linq join right join left join

            //var list = from a in info
            //           join b in classify_list
            //           on a.ID equals b.ClassifyID into joinData
            //           from c in joinData.DefaultIfEmpty()
            //           select new
            //           { 
            //               c.ClassifyID,
            //               QuestionCount=a!=null?a.TotalCount :0,
                          
            //               c.CreateTime ,
            //               c.ClassifyName ,
            //               c.EID,
            //               c.DataChange_LastTime 
            //           };


            var list = from a in classify_list
                       join b in info
                       on a.ClassifyID equals b.ID into joinData
                       from c in joinData.DefaultIfEmpty()
                       select new
                       {
                           a.ClassifyID,
                           QuestionCount = c != null ? c.TotalCount : 0,
                           a.CreateTime,
                           a.ClassifyName,
                           a.EID,
                           a.DataChange_LastTime
                       };