Return two relationship in one resultset - sql

Question

Below are the oversimplified inspired from my production schema.
Thus, I want to return all these information in one result set.
My desired result set
I have tried this query but it return wrong result.
SELECT u.*
,f.*
,uv.*
,v.*
FROM User u
LEFT JOIN UserFarm uf ON uf.UserID = u.ID
LEFT JOIN Farm f ON f.ID = uf.FarmID
LEFT JOIN FarmVehicle fv ON f.ID = fv.FarmID
LEFT JOIN UserVehicle uv ON u.ID = uv.UserID
LEFT JOIN Vehicle v ON fv.VehicleID = v.ID
WHERE u.ID = 1
Edit: This is the result from above query.
Could anyone advise me on this, I really need to return in the desired result.

Answer 1

You could build a query to return the data you want in the first row, and null in the columns you don't want for that row. Then create another query for the second row and use union all to combine the data together:
declare #UserVehicle table (UserID int, VehicleID int, IsService bit)
declare #User table (ID int, Name varchar(10))
declare #UserFarm table (UserID int, FarmID int)
declare #Farm table (ID int, Name varchar(10))
declare #FarmVehicle table (FarmID int, VehicleID int)
declare #Vehicle table (ID int, [Type] varchar(10), Name varchar(10))
insert into #UserVehicle values (1, 2, 1)
insert into #User values (1, 'Sam')
insert into #UserFarm values (1, 1)
insert into #Farm values (1, 'Flora')
insert into #FarmVehicle values (1, 1)
insert into #Vehicle values (1, 'Larry', 'Scania'), (2, 'Unknown', 'Civic')
select [User.ID] = u.ID
,[User.Name] = u.Name
,[Farm.ID] = f.ID
,[Farm.Name] = f.Name
,[UserVehicle.UserID] = null
,[UserVehicle.VehicleID] = null
,[UserVehicle.IsService] = null
,[Vehicle.ID] = v.ID
,[Vehicle.Name] = v.Name
from #User u
left join #UserFarm uf on u.ID = uf.UserID
left join #Farm f on uf.FarmID = f.ID
left join #FarmVehicle fv on f.ID = fv.VehicleID
left join #Vehicle v on fv.VehicleID = v.ID
union all
select [User.ID] = u.ID
,[User.Name] = u.Name
,[Farm.ID] = null
,[Farm.Name] = null
,[UserVehicle.UserID] = uv.UserID
,[UserVehicle.VehicleID] = uv.VehicleID
,[UserVehicle.IsService] = case when uv.IsService = 0 then 'No' else 'Yes' end
,[Vehicle.ID] = v.ID
,[Vehicle.Name] = v.Name
from #User u
left join #UserFarm uf on u.ID = uf.UserID
left join #UserVehicle uv on u.ID = uv.UserID
left join #Vehicle v on uv.VehicleID = v.ID
This query returns the following dataset:
User.ID User.Name Farm.ID Farm.Name UserVehicle.UserID UserVehicle.VehicleID UserVehicle.IsService Vehicle.ID Vehicle.Name
----------- ---------- ----------- ---------- ------------------ --------------------- --------------------- ----------- ------------
1 Sam 1 Flora NULL NULL NULL 1 Scania
1 Sam NULL NULL 1 2 Yes 2 Civic
If you do not want to see users who are not assigned to vehicles or farms, then change all left join to inner join.

Answer 2

Try with following query
SELECT U.*,T.* FROM (
SELECT F.FARMID,F.NAME AS NAM
,UV.*
,V.*
FROM VEHICLE V
LEFT JOIN FARMVEHICLE FV ON FV.VEHICLEID = V.ID
LEFT JOIN USERVEHICLE UV ON UV.VEHICLEID = V.ID
LEFT JOIN FARM F ON F.FARMID = FV.FARMID
LEFT JOIN USERFARM UF ON UF.FARMID = F.FARMID)T, USER U
Let me know if any issue in query.

Answer 3

You want to show a user's farms and vehicles. However farms and vehicles can be related, and in that case you want to show them together in a row rather than in separated rows.
Example: User1 is related to Farm1, Farm2, and Farm3 and to Vehicle1, Vehicle2, and Vehicle3. Moreover, Farm1 is related to Vehicle1 and Vehicle2 and Farm2 is also related to Vehicle1.
Then you want:
user | farm | vehicle
------+-------+---------
User1 | Farm1 | Vehicle1
User1 | Farm1 | Vehicle2
User1 | Farm2 | Vehicle1
User1 | Farm3 | -
User1 | - | Vehicle3
So the second and third columns show the relations of farms with vehicles. You get these with a full outer join. The join's ON clause is a bit tricky. You want the userid to match and the combination of farmid and vehicleid to be found in the bridge table farmvehicle. Here is one way to do this:
with rel as
(
select coalesce(uf.userid, uv.userid) as userid, uf.farmid, uv.vehicleid
from userfarm uf
full outer join uservehicle uv
on uf.userid = uv.userid
and exists (select * from farmvehicle fv where fv.farmid = uf.farmid
and fv.vehicleid = uv.vehicleid)
)
select u.name as user_name, f.name as farm_name, v.name as vehicle_name
from usr u
left join rel on u.id = rel.userid
left join farm f on f.id = rel.farmid
left join vehicle v on v.id = rel.vehicleid
order by user_name, farm_name, vehicle_name;
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