How to include non-matching rows? - sql

Question

This script is working as intended.
select a.Loc, Count(a.PID) as TotalVisit
from AccountCount as a
inner join Data as b
on a.PID = b.PID
where
cast(a.DateTime as date) between cast(b.ADateTime as date) and cast(b.DDateTime as date)
and year(a.DateTime)=2015
and month(a.DateTime)=05
group by a.Loc
order by a.Loc;
However, I need to include few more PID from Data table. These PID is not in AccountCount table.
select LocID, PID
from Data
where
and cast(ADateTime as date) = cast(DDateTime as date)
and year(ADateTime) = 2015
and month(ADateTime)=05
order by LocID;
In simple terms, I need to do union between the first script and the second script. I tried to right join the Data table but it didn't work.
Using the UNION ALL provided by xQbert, I get the result like.
Loc TotalVisit
1st floor 20
2nd floor 5
3rd floor 8
1st floor 2
It needs to be
Loc TotalVisit
1st floor 22
2nd floor 5
3rd floor 8
Please help.
Thank you.

Answer 1

I would think a right join would work so long as the ON criteria is setup correctly and the Where clause is moved to the join (as it makes the right join an inner join again if left in the where clause. (the outer join results in null records which are excluded by the where clause thus negating the outer join))
The union all doesn't allow for the aggregation of data. To me the outer join is the right thing to do here. We just need to understand the data better to make it work correctly. However, using union all you could simply sum up the results... using an outer query... but now that you've given some sample data I might be able to figure out why the outer join wasn't working)
Using union all ... (I'm about getting it working then improving it)
Select X.Loc, sum(X.TotalVisit) as TotalVisit
from (SELECT a.Loc as LOC, Count(a.PID) as TotalVisit
from AccountCount as a
inner join Data as b
on a.PID = b.PID
where
cast(a.DateTime as date) between cast(b.ADateTime as date) and cast(b.DDateTime as date)
group by a.Loc
UNION ALL
select LocID as LOC, count(PID)
from Data
where
and cast(ADateTime as date) = cast(DDateTime as date)
GROUP BY by LocID
) X
GROUP BY X.Loc
ORDER BY X.LOC
This leads me to this... which I think would work Take the first non-null value of location from AccountCount.Loc and Data.LocID and use it. Notice no where clause...
SELECT Coalesce(A.Loc, B.LocID) as Loc, count(B.PID) as TotalVisit
FROM Data B
LEFT JOIN AccountCount A
on B.PID = A.PID
and (cast(a.DateTime as date) between cast(b.ADateTime as date) and cast(b.DDateTime as date)
OR cast(B.ADateTime as date) = cast(B.DDateTime as date))
GROUP BY Coalesce(A.Loc, B.LocID)
Order by Coalesce(A.Loc, B.LocID)