update column value using a range group - sql

Question

Hi im new with sql queries i need help.
I have a table which have QuestionId from 0 to 8 but sometimes except zero a value can be repeated, what i want is top create a group from 0 to 8 and when other 0 occurs it will be a new group, instead of creating i want to give random number to SurveyID column.
QuestionID SurveyID
0 NULL
1 NULL
2 NULL
3 NULL
4 NULL
4 NULL
5 NULL
6 NULL
7 NULL
7 NULL
8 NULL
8 NULL
0 NULL
1 NULL
2 NULL
3 NULL
4 NULL
4 NULL
5 NULL
6 NULL
6 NULL
7 NULL
8 NULL
0 NULL
1 NULL
2 NULL
i want to update the surveyID in group from first 0 before second 0.
I want to give Unique random value to the group form 0 to 8 then again a new random value to 0 - 8
QuestionID SurveyID
0 8888
1 8888
2 8888
3 8888
4 8888
4 8888
5 8888
6 8888
7 8888
7 8888
8 8888
8 8888
0 1232
1 1232
2 1232
3 1232
I want this to be done.

Answer 1

You can use a CTE query to generate SurveyId the way you want. I assumed that your primary key column is named Id and table seq - please replace that. You can also use a different way to generate random numbers - up to you.
with cte as
(
select Id, questionId, convert(int, rand() * Id * 1000) as surverId
from seq
where questionId = 0
union all
select seq.Id, seq.questionId, cte.surverId
from seq
inner join cte on cte.Id + 1 = seq.Id
where seq.questionId <> 0
)
merge seq as target
using (select * from cte) as source (Id, questionId, surveyId)
on (target.Id = source.Id)
when matched then
update set target.SurveyId = source.surveyId;