How to self join this SQL - sql

Question

I have one table in my Database that has column names: buildNumber, result, versionStatus. Now in my SQL statement I want to display the 'buildNumber' where the 'versionStatus' is old and the 'result' is pass and where the versionStatus is new and the result is 'fail'. So I want to display anything that has a result of fail today but had a result of pass last time. So if I have these records in the DB (column separated by --):
build2--pass--old
build2--fail--new
The SQL statement should only display "build2" because it passed with "old" but now 'failed' with new version.
I have tried:
select *
from CSAResults.dbo.Details
where result = 'pass'
and versionStatus = 'Old'
and versionStatus IN (select CSAResults.dbo.Details.versionStatus
from CSAResults.dbo.Details
where versionStatus = 'New'
and result = 'fail')
but nothing is returned.
Thanks

Answer 1

This query does a self-joins of Details table to get the result you want.
SELECT distinct new.buildNumber
FROM CSAResults.dbo.Details old
JOIN CSAResults.dbo.Details new ON old.buildNumber = new.buildNumber
WHERE old.result = 'pass'
AND old.versionStatus = 'Old'
AND new.result='fail'
AND new.versionStatus='New'
I added the distinct in the select clause so you wouldn't get duplicate results if there were multiple old versions of the build that had passed

Answer 2

Your existing query should work if you change the IN condition to be:
and buildNumber IN (select CSAResults.dbo.Details.buildNumber
Alternatively, a better performing query might be:
Select buildNumber
from CSAResults.dbo.Details
group by buildNumber
having count(distinct case
when result = 'pass' and versionStatus = 'Old' then 1
when result = 'fail' and versionStatus = 'New' then 2
end) = 2

Answer 3

An alternative would be to use an INNER JOIN as so:
select t.*
from CSAResults.dbo.Details t INNER JOIN (SELECT t2.buildNumber
FROM CSAResults.dbo.Details t2
WHERE t2.versionStatus = 'New'
and t2.result = 'fail') t1
ON t.buildNumber = t1.buildNumber
where t.result = 'pass'
and t.versionStatus = 'Old'

Answer 4

Nothing returned? Hardly surprising: you're trying to assert
(VersionStatus='New') = (VersionStatus='Old')
Try something like this instead
select *
from CSAResults.dbo.Details
where result = 'pass'
and versionStatus = 'Old'
and buildNumber IN (select CSAResults.dbo.Details.buildNumber from CSAResults.dbo.Details
where versionStatus = 'New'
and result = 'fail')