Consolidating 2 Recursive CTE Statements - sql-server

Question

The following statement uses 2 separate recursive CTE statements to build a list of steps from a starting location to an ending location based on trips. The desired output is correct, however I am wondering if it is possible to consolidate the 2 CTE statements into one.
The difficulty I am having is relating the endLocation to the startLocation in the first recursive iteration cte1.
The database is SQL Server 2017. I have added the SQL fiddle below:
[SQL Fiddle][1]
SQL Server 2017 Schema Setup:
Create Table TripLocation
(TripID int,
LocationID int,
StopOrder int
)
Create table FromTo
(tripID int,
fromLocationID int,
fromStopOrder int,
toLocationID int,
toStopOrder int
)
Create table cte1Temp
(startTripID int,
startLocationID int,
tripID int,
fromLocationID int,
toLocationID int,
step int)
Create table cte2Temp
(startTripID int,
startLocationID int,
endLocationID int,
tripID int,
fromLocationID int,
toLocationID int,
step int)
--LIST OF LOCATIONS FOR EACH TRIP
Insert into TripLocation
Values
(1,1,0),
(1,2,1),
(1,1,2),
(2,2,0),
(2,3,1),
(2,2,2),
(3,3,0),
(3,4,1),
(3,3,2)
--LIST OF POSSIBLE TO/FROM COMBINATIONS FOR EACH TRIP BASED ON STOPORDER
insert into FromTo
select
FromLocation.tripID,
FromLocation.LocationID [fromLocationID],
FromLocation.StopOrder [fromStopOrder],
ToLocation.LocationID [toLocationID],
ToLocation.StopOrder [toStopOrder]
from
TripLocation FromLocation
join TripLocation ToLocation
on FromLocation.tripID = ToLocation.tripID
and ToLocation.StopOrder >= FromLocation.StopOrder
and FromLocation.LocationID <> ToLocation.LocationID
;
--FIND ALL POSSIBLE END LOCATIONS FOR EACH START LOCATION IF TRIPS SHARE A COMMON LOCATION
with cte1 as
(
select
tripID [startTripID],
fromLocationID [startLocationID],
tripID,
fromLocationID,
toLocationID,
1 [step]
from
FromTo
union all
select
anchor.startTripID,
anchor.startLocationID,
member.tripID,
member.fromLocationID,
member.toLocationID,
anchor.step + 1 [step]
from
FromTo member
join cte1 anchor
on anchor.toLocationID = member.fromLocationID
and member.toLocationID <> anchor.fromLocationID
and member.tripID <> anchor.tripID
)
insert into cte1Temp
select
*
from
cte1
;
--GENERATE PLAN FOR EACH START LOCATION TO AN END LOCATION
with cte2 as
(
select
startTripID,
StartLocationID,
ToLocationID [EndLocationID],
tripID,
FromLocationID,
ToLocationID,
step
from
cte1Temp
union all
select
b.startTripID,
b.StartLocationID,
b.ToLocationID,
a.tripID,
a.FromLocationID,
a.ToLocationID,
a.step
from
cte1Temp b
join CTE2 a
on a.endLocationID = b.FromLocationID
and a.startLocationID = b.startLocationID
)
insert into cte2Temp
select
*
from
cte2
Query 1:
select
*
from
cte2Temp
order by
startlocationID, endLocationID, step
Results:
| startTripID | startLocationID | endLocationID | tripID | fromLocationID | toLocationID | step |
|-------------|-----------------|---------------|--------|----------------|--------------|------|
| 1 | 1 | 2 | 1 | 1 | 2 | 1 |
| 1 | 1 | 3 | 1 | 1 | 2 | 1 |
| 1 | 1 | 3 | 2 | 2 | 3 | 2 |
| 1 | 1 | 4 | 1 | 1 | 2 | 1 |
| 1 | 1 | 4 | 2 | 2 | 3 | 2 |
| 1 | 1 | 4 | 3 | 3 | 4 | 3 |
| 1 | 2 | 1 | 1 | 2 | 1 | 1 |
| 2 | 2 | 3 | 2 | 2 | 3 | 1 |
| 2 | 2 | 4 | 2 | 2 | 3 | 1 |
| 2 | 2 | 4 | 3 | 3 | 4 | 2 |
| 2 | 3 | 1 | 2 | 3 | 2 | 1 |
| 2 | 3 | 1 | 1 | 2 | 1 | 2 |
| 2 | 3 | 2 | 2 | 3 | 2 | 1 |
| 3 | 3 | 4 | 3 | 3 | 4 | 1 |
| 3 | 4 | 1 | 3 | 4 | 3 | 1 |
| 3 | 4 | 1 | 2 | 3 | 2 | 2 |
| 3 | 4 | 1 | 1 | 2 | 1 | 3 |
| 3 | 4 | 2 | 3 | 4 | 3 | 1 |
| 3 | 4 | 2 | 2 | 3 | 2 | 2 |
| 3 | 4 | 3 | 3 | 4 | 3 | 1 |

Answer 1

You can try this
Create Table TripLocation
(TripID int,
LocationID int,
StopOrder int
)
Create table FromTo
(tripID int,
fromLocationID int,
fromStopOrder int,
toLocationID int,
toStopOrder int
)
Create table cte1Temp
(startTripID int,
startLocationID int,
tripID int,
fromLocationID int,
toLocationID int,
step int,
path varchar(max)
)
--LIST OF LOCATIONS FOR EACH TRIP
Insert into TripLocation
Values
(1,1,0),
(1,2,1),
(1,1,2),
(2,2,0),
(2,3,1),
(2,2,2),
(3,3,0),
(3,4,1),
(3,3,2)
--LIST OF POSSIBLE TO/FROM COMBINATIONS FOR EACH TRIP BASED ON STOPORDER
insert into FromTo
select
FromLocation.tripID,
FromLocation.LocationID [fromLocationID],
FromLocation.StopOrder [fromStopOrder],
ToLocation.LocationID [toLocationID],
ToLocation.StopOrder [toStopOrder]
from
TripLocation FromLocation
join TripLocation ToLocation
on FromLocation.tripID = ToLocation.tripID
and ToLocation.StopOrder >= FromLocation.StopOrder
and FromLocation.LocationID <> ToLocation.LocationID
;
--FIND ALL POSSIBLE END LOCATIONS FOR EACH START LOCATION IF TRIPS SHARE A COMMON LOCATION
with cte1 as
(
select
tripID [startTripID],
fromLocationID [startLocationID],
tripID,
fromLocationID,
toLocationID,
1 [step],
cast('1_' + ltrim(str(tripID)) + '-' + ltrim(str(tolocationID)) as varchar(max)) [path]
from
FromTo
union all
select
anchor.startTripID,
anchor.startLocationID,
member.tripID,
member.fromLocationID,
member.toLocationID,
anchor.step + 1 [step],
anchor.path + ',' + ltrim(str(anchor.step + 1)) + '_' + + ltrim(str(member.tripID)) + '-' + ltrim(str(member.toLocationID))
from
FromTo member
join cte1 anchor
on anchor.toLocationID = member.fromLocationID
and member.toLocationID <> anchor.fromLocationID
and member.tripID <> anchor.tripID
)
insert into cte1Temp
select
*
from
cte1
;
select
StartLocationID,
TolocationId,
Substring(Value, 1,Charindex('-', Value)-1) as Trip,
Substring(Value, Charindex('-', Value)+1, LEN(Value)) as CrossingLocationID
from
cte1Temp
CROSS APPLY STRING_SPLIT(path, ',')
order by StartLocationId, ToLocationId, Trip
Results:
StartLocationID TolocationId Trip CrossingLocationID
1 2 1_1 2
1 3 1_1 2
1 3 2_2 3
1 4 1_1 2
1 4 2_2 3
1 4 3_3 4
2 1 1_1 1
2 3 1_2 3
2 4 1_2 3
2 4 2_3 4
3 1 1_2 2
3 1 2_1 1
3 2 1_2 2
3 4 1_3 4
4 1 1_3 3
4 1 2_2 2
4 1 3_1 1
4 2 1_3 3
4 2 2_2 2
4 3 1_3 3