Recursive CTE to find all records SQL Server - sql

Question

I am having below table structure. I want to write a recursive cte to get the bottom most table result.
Highly appreciate your help.
CREATE TABLE Jobcard (
jobcard_id INT NOT NULL PRIMARY KEY,
jobcard_name varchar(20) NOT NULL,
);
CREATE TABLE Vehicle (
vehicle_id INT NOT NULL PRIMARY KEY,
vehicle_name varchar(20) NOT NULL
);
CREATE TABLE Jobacard_vehicle (
jobcard_id INT NOT NULL,
vehicle_id INT NOT NULL
);
INSERT INTO Jobcard (jobcard_id, jobcard_name) VALUES
(1, 'Job1'),(2, 'Job2'),(3, 'Job3'),
(4, 'Job4'),(5, 'Job5'),(6, 'Job6'),
(7, 'Job7'),(8, 'Job8'),(9, 'Job9');
INSERT INTO Vehicle (vehicle_id, vehicle_name) VALUES
(1, 'Vehicle1'),(2, 'Vehicle2'),(3, 'Vehicle3'),
(4, 'Vehicle4'),(5, 'Vehicle5'),(6, 'Vehicle6');
INSERT INTO Jobacard_vehicle (jobcard_id, vehicle_id) VALUES
(3, 1),(4, 2),(5, 3),
(9, 6),(7, 2),(5, 4),
(8, 4),(6, 1),(3, 5);
jobcard_id, vehicle_id
--------------------------
3 1
4 2
5 3
9 6
7 2
5 4
8 4
6 1
3 5
I want to get this result from Jobacard_vehicle table when I pass the vehicle id as 3 as
vehicle id 3 is having jobcard 5
jobcard 5 is having vehicle 4
again vehicle 4 referred to jobcard 8
means all the jobcard refered by 3 or its counter part jobcards vehicles
jobcard_id, vehicle_id
--------------------------
5 3
5 4
8 4
Thank you.

Answer 1

Try to save full path and check it in the next recursion
DECLARE #startVehicleID int=3
;WITH vehCTE AS(
SELECT jobcard_id,vehicle_id,CAST(CONCAT('(',jobcard_id,',',vehicle_id,')') AS varchar(MAX)) [path]
FROM Jobacard_vehicle
WHERE vehicle_id=#startVehicleID
UNION ALL
SELECT v.jobcard_id,v.vehicle_id,c.[path]+CONCAT('(',v.jobcard_id,',',v.vehicle_id,')')
FROM Jobacard_vehicle v
JOIN vehCTE c ON (v.jobcard_id=c.jobcard_id OR v.vehicle_id=c.vehicle_id) AND CHARINDEX(CONCAT('(',v.jobcard_id,',',v.vehicle_id,')'),c.[path])=0
)
SELECT *
FROM vehCTE
ORDER BY [path]
If you need to check Job->Vehicle->Job->Vehicle->... then I think you can use the following
DECLARE #startVehicleID int=3
;WITH vehCTE AS(
SELECT
jobcard_id,
vehicle_id,
CAST(CONCAT('(',jobcard_id,',',vehicle_id,')') AS varchar(MAX)) [path],
1 NextIsJob
FROM Jobacard_vehicle
WHERE vehicle_id=#startVehicleID
UNION ALL
SELECT
v.jobcard_id,
v.vehicle_id,
c.[path]+CONCAT('(',v.jobcard_id,',',v.vehicle_id,')'),
IIF(c.NextIsJob=1,0,1)
FROM Jobacard_vehicle v
JOIN vehCTE c ON ((c.NextIsJob=1 AND v.jobcard_id=c.jobcard_id) OR (c.NextIsJob=0 AND v.vehicle_id=c.vehicle_id)) AND CHARINDEX(CONCAT('(',v.jobcard_id,',',v.vehicle_id,')'),c.[path])=0
)
SELECT *
FROM vehCTE
ORDER BY [path]