increasing value with condition on oracle - sql

Question

How to add an increment value (not summarize) with some condition on another column?
I'm using Oracle-like DBMS, named Tibero, for simple example i want to produce this data
ROWNUM GRP_STRT GRP_NO SLBY
1 1 1 1
2 1 1 1
3 1 1 1
4 1 1 1
5 1 1 1
6 1 2 0
7 1 2 0
8 1 3 1
9 1 3 1
10 1 3 1
11 1 4 0
12 1 5 1
Column SLBY is for Buy/Sell code (0=Buy, 1=Sell) then every changing type of transaction, column GRP_NO increasing (but it's not grouping by SLBY column)
SELECT CASE
WHEN ROWNUM = 1 THEN GRP_NO
WHEN ROWNUM <> 1 AND SLBY = LAG(SLBY,1) over (ORDER BY ROWNUM) THEN LAG(GRP_STRT,1) over (ORDER BY ROWNUM) - 1
WHEN ROWNUM <> 1 AND SLBY_DSTN_CD <> LAG(SLBY_DSTN_CD,1) over (ORDER BY ROWNUM) THEN LAG(GRP_STRT,1) over (ORDER BY ROWNUM) + 1
END TARGET_GROUPING
, A.*
FROM SOME_TABLE
I tried with that query but instead of getting what i want like in the picture above, I produced a GRP_NO like 1 1 1 1 1 2 1 1 1 1 2 1 1 1 (first change SLBY only)
Apologies for my bad english and bad explanation, I'll explain more if need further information, thanks for your help!

Answer 1

As far as I understood your problem,
You are trying to calculate GRP_NO from ROWNUM, GRP_STRT, GRP_NO, and SLBY.
I have created the following query for you.
You can check the logic and apply it in your code accordingly:
SELECT
RN,
GRP_STRT,
SUM(CASE
WHEN PREV_SLBY_DSTN_CD IS NULL
OR PREV_SLBY_DSTN_CD <> SLBY_DSTN_CD THEN 1
END) OVER(
ORDER BY
RN
) AS GRP_NO,
SLBY_DSTN_CD AS SLBY
FROM
(
SELECT
RN,
LAG(SLBY_DSTN_CD) OVER(
ORDER BY
RN
) AS PREV_SLBY_DSTN_CD,
SLBY_DSTN_CD,
GRP_STRT
FROM
(SELECT ROWNUM RN, .... FROM SOME_TABLE) A
)
This code is to generate the output as shown in question:
ROWNUM GRP_STRT GRP_NO SLBY
1 1 1 1
2 1 1 1
3 1 1 1
4 1 1 1
5 1 1 1
6 1 2 0
7 1 2 0
8 1 3 1
9 1 3 1
10 1 3 1
11 1 4 0
12 1 5 1
Cheers!!