How to do this query against MySQL database table? - mysql

Question

I was given a task to show the CPU usage trend as part of a building process which also do regression test.
Each individual test case run has a record in the table RegrCaseResult. The RegrCaseResult table looks something like this:
id projectName ProjectType returnCode startTime endTime totalMetrics
1 'first' 'someType' 16 'someTime' 'someOtherTime' 222
The RegrCaseResult.totalMetrics is a special key which links to another table called ThreadMetrics through ThreadMetrics.id.
Here is how ThreadMetrics will look like:
id componentType componentName cpuTime linkId
1 'Job Totals' 'Job Totals' 'totalTime' 34223
2 'parser1' 'parser1' 'time1' null
3 'parser2' 'generator1' 'time2' null
4 'generator1' 'generator1' 'time3' null
------------------------------------------------------
5 'Job Totals' 'Jot Totals' 'totalTime' 9899
...
The rows with the compnentName 'Job Totals' is what the totalMetrics from RegrCaseResult table will link to and the 'totalTime' is what I am really want to get given a certain projectType. The 'Job Totals' is actually a summation of the other records - in the above example, the summation of time1 through time3. The linkId at the end of table ThreadMetrics can link back to RegrCaseResult.id.
The requirements also states I should have a way to enforce the condition which only includes those projects which have a consistent return code during certain period. That's where my initial question comes from as follows:
I created the following simple table to show what I am trying to achieve:
id projectName returnCode
1 'first' 16
2 'second' 16
3 'third' 8
4 'first' 16
5 'second' 8
6 'first' 16
Basically I want to get all the projects which have a consistent returnCode no matter what the returnCode values are. In the above sample, I should only get one project which is "first". I think this would be simple but I am bad when it comes to database. Any help would be great.
I tried my best to make it clear. Hope I have achieved my goal.

Answer 1

Here is an easy way:
select projectname
from table t
group by projectname
having min(returncode) = max(returncode);
If the min() and max() values are the same, then all the values are the same (unless you have NULL values).
EDIT:
To keep 'third' out, you need some other rule, such as having more than one return code. So, you can do this:
select projectname
from table t
group by projectname
having min(returncode) = max(returncode) and count(*) > 1;

Answer 2

select projectName from projects
group by projectName having count(distinct(returnCode)) = 1)
This would also return projects which has only one entry.
How do you want to handle them?
Working example: http://www.sqlfiddle.com/#!2/e7338/8

Answer 3

This should do it:
SELECT COUNT(ProjectName) AS numCount, ProjectName FROM (
SELECT ProjectName FROM Foo
GROUP BY ProjectName, ReturnCode
) AS Inside
GROUP BY Inside.ProjectName
HAVING numCount = 1
This groups all the ProjectNames by their names and return codes, then selects those that only have a single return code listed.
SQLFiddle Link: http://sqlfiddle.com/#!2/c52b6/11/0

Answer 4

You can try something like this with Not Exists:
Select Distinct ProjectName
From Table A
Where Not Exists
(
Select 1
From Table B
Where B.ProjectName = A.ProjectName
And B.ReturnCode <> A.ReturnCode
)
I'm not sure exactly what you're selecting, so you can change the Select statement to what you need.