Correlative by group with special criteria - sql

Question

We need to get the result of the column NEED, need the correlative grouped by the GROUP column in the order of the ORDER column and that increases when the FLAG column changes.
GROUP ORDER FLAG NEED
1111 1 0 1
1111 2 0 1
1111 3 1 2
1111 4 1 2
1111 5 1 2
1111 6 1 2
1111 7 1 2
1111 8 0 3
1111 9 1 4
1111 10 1 4
1111 11 0 5
1111 12 0 5
1111 13 0 5
6666 1 0 1
6666 2 0 1
6666 3 1 2
6666 4 1 2
We try the following code, but we need something cleaner with support for SQL Server 2008
if object_id('tempdb..#temp2','u') is not NULL
drop table #temp2
SELECT *
,ROW_NUMBER() OVER(oRDER BY (SELECT NULL)) RN
INTO #temp2
FROM DBO.PRUEBA​
SELECT T1.*
,SUM(CASE WHEN T1.NUM_GROUP = T2.NUM_GROUP and t1.NUM_FLAG = t2.NUM_FLAG THEN 0 ELSE 1 END) OVER (PARTITION BY T1.NUM_GROUP ORDER BY T1.rn)[Rank]
FROM #temp2 T1
LEFT JOIN #temp2 T2 ON T1.rn = T2.rn+1
order by t1.NUM_GROUP, t1.NUM_ORDER
I share the creation of tables and records
CREATE TABLE DBO.PRUEBA
(
NUM_GROUP INT,
NUM_ORDER INT,
NUM_FLAG INT
)
INSERT INTO DBO.PRUEBA VALUES (1111, 1, 0)
INSERT INTO DBO.PRUEBA VALUES (1111, 2, 0)
INSERT INTO DBO.PRUEBA VALUES (1111, 3, 1)
INSERT INTO DBO.PRUEBA VALUES (1111, 4, 1)
INSERT INTO DBO.PRUEBA VALUES (1111, 5, 1)
INSERT INTO DBO.PRUEBA VALUES (1111, 6, 1)
INSERT INTO DBO.PRUEBA VALUES (1111, 7, 1)
INSERT INTO DBO.PRUEBA VALUES (1111, 8, 0)
INSERT INTO DBO.PRUEBA VALUES (1111, 9, 1)
INSERT INTO DBO.PRUEBA VALUES (1111, 10, 1)
INSERT INTO DBO.PRUEBA VALUES (1111, 11, 0)
INSERT INTO DBO.PRUEBA VALUES (1111, 12, 0)
INSERT INTO DBO.PRUEBA VALUES (1111, 13, 0)
INSERT INTO DBO.PRUEBA VALUES (6666, 1, 0)
INSERT INTO DBO.PRUEBA VALUES (6666, 2, 0)
INSERT INTO DBO.PRUEBA VALUES (6666, 3, 1)
INSERT INTO DBO.PRUEBA VALUES (6666, 4, 1)
SELECT * FROM DBO.PRUEBA

Answer 1

A possible optimalization is to first create the temporary table.
Instead of using a SELECT INTO.
And with a primary key that benefits the self-join that's used to get the previous NUM_FLAG.
CREATE TABLE DBO.PRUEBA
(
NUM_GROUP INT NOT NULL,
NUM_ORDER INT NOT NULL,
NUM_FLAG INT NOT NULL,
PRIMARY KEY (NUM_GROUP, NUM_ORDER)
);
GO
INSERT INTO DBO.PRUEBA
(NUM_GROUP, NUM_ORDER, NUM_FLAG)
VALUES
(1111, 1, 0)
,(1111, 2, 0)
,(1111, 3, 1)
,(1111, 4, 1)
,(1111, 5, 1)
,(1111, 6, 1)
,(1111, 7, 1)
,(1111, 8, 0)
,(1111, 9, 1)
,(1111, 10, 1)
,(1111, 11, 0)
,(1111, 12, 0)
,(1111, 13, 0)
,(6666, 1, 0)
,(6666, 2, 0)
,(6666, 3, 1)
,(6666, 4, 1)
IF OBJECT_ID('tempdb..#tmpPRUEBA', 'U') IS NOT NULL
DROP TABLE #tmpPRUEBA;
CREATE TABLE #tmpPRUEBA
(
NUM_GROUP INT NOT NULL,
RN_GROUP INT NOT NULL,
NUM_ORDER INT NOT NULL,
NUM_FLAG INT NOT NULL,
PRIMARY KEY (NUM_GROUP, RN_GROUP)
);
GO
INSERT INTO #tmpPRUEBA
(NUM_GROUP, NUM_ORDER, NUM_FLAG, RN_GROUP)
SELECT NUM_GROUP, NUM_ORDER, NUM_FLAG
, ROW_NUMBER() OVER (
PARTITION BY NUM_GROUP
ORDER BY NUM_ORDER) AS RN_GROUP
FROM DBO.PRUEBA;
GO
SELECT
t1.NUM_GROUP,
t1.NUM_ORDER,
t1.NUM_FLAG,
SUM(CASE
WHEN t1.NUM_FLAG = t2.NUM_FLAG
THEN 0
ELSE 1
END)
OVER (PARTITION BY t1.NUM_GROUP
ORDER BY t1.RN_GROUP) AS [Rank]
FROM #tmpPRUEBA t1
LEFT JOIN #tmpPRUEBA t2
ON t2.NUM_GROUP = t1.NUM_GROUP
AND t2.RN_GROUP = t1.RN_GROUP - 1;
GO
NUM_GROUP | NUM_ORDER | NUM_FLAG | Rank
--------: | --------: | -------: | ---:
1111 | 1 | 0 | 1
1111 | 2 | 0 | 1
1111 | 3 | 1 | 2
1111 | 4 | 1 | 2
1111 | 5 | 1 | 2
1111 | 6 | 1 | 2
1111 | 7 | 1 | 2
1111 | 8 | 0 | 3
1111 | 9 | 1 | 4
1111 | 10 | 1 | 4
1111 | 11 | 0 | 5
1111 | 12 | 0 | 5
1111 | 13 | 0 | 5
6666 | 1 | 0 | 1
6666 | 2 | 0 | 1
6666 | 3 | 1 | 2
6666 | 4 | 1 | 2
db<>fiddle here