How to get alternate row using SQL query? - sql

Question

I have a requirement which I need to produce the result that returns alternately 1 and 0.
SELECT *
FROM
(SELECT
id
,itemNo
,convert(int,tStationsType_id) as tStationsType_id
,tSpecSetpoint_descriptions_id
,SetpointValue
,rowEvenOdd
FROM
TEST S
INNER JOIN
(SELECT
itemNo AS IM, tStationsType_id as ST,
ROW_NUMBER() OVER(PARTITION BY itemNo ORDER BY itemNo) % 2 AS rowEvenOdd
FROM TEST
GROUP BY itemNo, tStationsType_id) A ON S.itemNo = A.IM
AND S.tStationsType_id = A.ST) t
WHERE
itemno = '1000911752202'
ORDER BY
tStationsType_id
The result I get is something like below.
I would like to produce alternate 1 and 0 in rowEvenOdd. However I notice it I can't get it alternate if I order by tStationsType_id.
So basically, what I want is when the
StationsType_id = 2, then rowEvenOdd = 0
StationsType_id = 3, then rowEvenOdd = 1
StationsType_id = 6, then rowEvenOdd = 0
StationsType_id = 8, then rowEvenOdd = 1
StationsType_id = 10, then rowEvenOdd = 0
Can someone help me with this query?
Thanks.

Answer 1

If you just need alternating 0 and 1 in the result set, use SEQUENCE like this:
CREATE SEQUENCE EvenOdd
START WITH 0
INCREMENT BY 1
MAXVALUE 1
MINVALUE 0
CYCLE;
GO
SELECT SalesId, NEXT VALUE FOR EvenOdd as EvenOddColumn FROM Sales
DROP SEQUENCE EvenOdd
To learn more, go to the MSDN page on sequences here: https://msdn.microsoft.com/en-us/library/ff878091.aspx

Answer 2

you can Use case when then
SELECT
case
when exists (SELECT 1 FROM StationsTypeMaster
M WHERE M.StationsType_id=A.StationsType_id)
then 1
else 0 end as rowEvenOdd
,*
FROM
(
select id
,itemNo
,convert(int,tStationsType_id) as tStationsType_id
,tSpecSetpoint_descriptions_id
,SetpointValue
,rowEvenOdd from TEST S
inner join
(select itemNo AS IM,tStationsType_id as ST,
ROW_NUMBER() OVER(PARTITION BY itemNo ORDER BY itemNo)%2 AS rowEvenOdd
from TEST
group by itemNo,tStationsType_id
)A
on S.itemNo = A.IM
and S.tStationsType_id = A.ST) t
where itemno = '1000911752202'
order by tStationsType_id

Answer 3

Use DENSE_RANK instead of ROW_NUMBER:
SELECT * FROM
(
SELECT
id,
itemNo
convert(int,tStationsType_id) as tStationsType_id,
tSpecSetpoint_descriptions_id,
SetpointValue,
(DENSE_RANK() OVER(ORDER BY CAST(A.ST as INT)) - 1)%2 AS rowEvenOdd
FROM
TEST S
JOIN
(
SELECT
itemNo AS IM,
tStationsType_id as ST
FROM
TEST
GROUP BY
itemNo,tStationsType_id
)A
ON
S.itemNo = A.IM
and S.tStationsType_id = A.ST
) t
WHERE
itemno = '1000911752202'
ORDER BY
tStationsType_id