FIll in missing months

Try this

declare @months table
(
    monthnum int
 --,  mnthname varchar(3)
)
insert into @months  

select MonthInt
from (
select 1 as MonthInt union all select 2  union all  select 3  union all   select 4 union all 
select 5 as MonthInt union all select 6  union all  select 7  union all   select 8 union all 
select 9 as MonthInt union all select 10  union all  select 11  union all   select 12 
)M

declare @rider table(id int, rdt date, distance int);
insert into @rider values
(1, dateadd(m,-5,Getdate()),200),
(1, dateadd(m,-4,Getdate()),500),
(1, dateadd(m,-2,Getdate()),100),
(1, dateadd(m,-1,Getdate()),1000),
(1, dateadd(m,0,Getdate()),100),
(1, dateadd(m,2,Getdate()),550),
(1, dateadd(m,4,Getdate()),560);

with cte as 
(select distinct id as riderid, m.monthnum from @rider r ,@months m )
select * from cte c left join @rider r on c.riderid=r.id and c.monthnum=month(r.rdt)

---

Satheesh

My Blog