SQL Server 2008 Group Based on a Sequence - sql

Question

I'm struggling to find if this is possible to use SQL Server 2008 to assign a sequence without having to use cursors. Let's say I have the following table which defines a driver's driving route going from one location to another (null means he is going from home):
RouteID SourceLocationID DestinationLocationID DriverID Created Updated
------- ---------------- --------------------- -------- ------- -------
1 NULL 219 1 10:20 10:23
2 219 266 1 10:21 10:24
3 266 NULL 1 10:22 10:25
4 NULL 54 2 10:23 10:26
5 54 NULL 2 10:24 10:27
6 NULL 300 1 10:25 10:28
7 300 NULL 1 10:26 10:29
I want to group the records between the rows where sourceLID is NULL and the destinationLID is null, so I get the following (generating a sequence number for each grouping set):
DriverID DestinationLocationID TripNumber
-------- --------------------- ----------
1 219 1 (his first trip)
1 266 1
1 300 2 (his second trip)
2 54 1
Is there a way I could use GROUP BY here rather than cursors?

Answer 1

a quick try:
with cte as
( select DestinationLocationID
, DriverID
, tripid = row_number()
over ( partition by driverid
order by DestinationLocationID)
from table1
where sourcelocationid is NULL
UNION ALL
select table1.DestinationLocationID
, table1.DriverID
, cte.tripid
from table1
join cte on table1.SourceLocationID=cte.DestinationLocationID
and table1.DriverID=cte.DriverID
where cte.DestinationLocationID is not null
)
select * from cte

Answer 2

Try this:
select driverid, destinationlocationid, count(destinationlocationid) from
(
select driverid, destinationlocationid from table1 where sourcelocationid is NULL
union all
select driverid, sourcelocationid from table1 where destinationlocationid is NULL
)A group by driverid, destinationlocationid

Answer 3

Try this,
Declare #t table(RouteID int, SourceLocationID int,DestinationLocationID int
,DriverID int,Created time, Updated time)
insert into #t
values(1, NULL, 219, 1, '10:20','10:23'),
(2 ,219,266, 1, '10:21','10:24'),
(3,266, NULL, 1, '10:22','10:25'),
(4, NULL, 54, 2, '10:23','10:26'),
(5,54, NULL, 2, '10:24','10:27'),
(6,NULL,300, 1, '10:25','10:28'),
(7,300,NULL, 1, '10:26','10:29')
;
WITH CTE
AS (
SELECT *
,ROW_NUMBER() OVER (
PARTITION BY DriverID ORDER BY Created
) RN
FROM #t
)
,CTE1
AS (
SELECT *
,1 TripNumber
FROM CTE
WHERE RN = 1
UNION ALL
SELECT A.*
,CASE
WHEN A.SourceLocationID IS NULL
THEN B.TripNumber + 1
ELSE B.TripNumber
END
FROM CTE1 B
INNER JOIN CTE A ON B.DriverID = A.DriverID
WHERE A.RN > B.RN
)
SELECT DISTINCT DestinationLocationID
,DriverID
,TripNumber
FROM CTE1
WHERE DestinationLocationID IS NOT NULL
ORDER BY DriverID

Answer 4

Use a correlated sub-query to count previous trips, plus 1 to get this trip number.
select DriverID,
DestinationLocationID,
(select count(*) + 1
from routes t2
where t1.DriverID = t2.DriverID
and t1.RouteID > t2.RouteID
and DestinationLocationID IS NULL) as TripNumber
from routes t1
where DestinationLocationID IS NOT NULL
order by DriverID, DestinationLocationID;
Executes like this:
SQL>select DriverID,
SQL& DestinationLocationID,
SQL& (select count(*) + 1
SQL& from routes t2
SQL& where t1.DriverID = t2.DriverID
SQL& and t1.RouteID > t2.RouteID
SQL& and DestinationLocationID IS NULL) as TripNumber
SQL&from routes t1
SQL&where DestinationLocationID IS NOT NULL
SQL&order by DriverID, DestinationLocationID;
DriverID DestinationLocationID TripNumber
=========== ===================== ============
1 219 1
1 266 1
1 300 2
2 54 1
4 rows found