How do I select the items based on their adjacent equality?

Question

In the below table,
    DECLARE @t1 TABLE(id INT,NAME VARCHAR(MAX))
    INSERT INTO @t1 VALUES(1,'test')
    INSERT INTO @t1 VALUES(2,'test')
    INSERT INTO @t1 VALUES(3,'best')
    INSERT INTO @t1 VALUES(4,'rest')
    INSERT INTO @t1 VALUES(5,'rest')
how can I select the records that have equals values coming adjacently? That is I am running an SQL job. It should take the adjacent equal value  count for its processing. In the below table, first time the job is running it should take count as 2 the
2nd time job is running it should be 1. Third time it should be 2. What is the query that will fetch the cont of equal records for name column? In case no equal columns it should be 1. Please help
mayooran99

Answer 1

Hi
Try the following code.
DECLARE @t1 TABLE(id INT,NAME VARCHAR(MAX))
INSERT INTO @t1 VALUES(1,'test')
INSERT INTO @t1 VALUES(2,'test')
INSERT INTO @t1 VALUES(3,'best')
INSERT INTO @t1 VALUES(4,'rest')
INSERT INTO @t1 VALUES(5,'rest')
INSERT INTO @t1 VALUES(6,'test')
INSERT INTO @t1 VALUES(7,'best')
INSERT INTO @t1 VALUES(8,'best')
INSERT INTO @t1 VALUES(9,'vest')
--ranking adjacent names, running total
SELECT rs.id, rs.NAME, ROW_NUMBER() over (partition by name, nxt_id order by id) RankingCount
FROM (
SELECT nxt.id, nxt.NAME,(SELECT min(s.id)
FROM @t1 s
WHERE s.name <> nxt.name
AND s.id > nxt.id
) as nxt_id
FROM @t1 nxt) rs
ORDER BY rs.id;
--code to just return the totals
with cteTotals
as
SELECT rs.id, rs.NAME, ROW_NUMBER() over (partition by name, nxt_id order by id) RankingCount, nxt_id, ROW_NUMBER() over (partition by name, nxt_id order by id desc) Ranking
FROM (
SELECT nxt.id, nxt.NAME,(SELECT min(s.id)
FROM @t1 s
WHERE s.name <> nxt.name
AND s.id > nxt.id
) as nxt_id
FROM @t1 nxt) rs
select Name, RankingCount
from cteTotals
WHERE Ranking=1
order by id
The first query keeps a running total of adjacent names, the second one just reports the totals