linq 左连接和有连接

linq 左连接写法  ，注意：这里主要第二个集合有可能为空。需要判断

1
var leftJoinSql = from student in  Student
                  join book in  Book on student.ID equals book.StudentID into temp
                  from tt in temp.DefaultIfEmpty()
                  select new
                   {
                       sname= student.Name,
                       bname = tt==null?"":tt.Name//这里主要第二个集合有可能为空。需要判断
                   };

linq 有连接

 2 var rightJoinSql = from book in Book
                   join stu in Student on book.StudentID equals stu.ID into joinTemp
                   from tmp in joinTemp.DefaultIfEmpty()
                   select new { 
                      sname=tmp==null?"":tmp.Name,
                      bname=book.Name
                    };