如何自我加入这个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

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 2

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 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')