Conditional Count on a field

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SELECT  Priority, COALESCE(cnt, 0)
FROM    (
SELECT  1 AS Priority
UNION ALL
SELECT  2 AS Priority
UNION ALL
SELECT  3 AS Priority
UNION ALL
SELECT  4 AS Priority
UNION ALL
SELECT  5 AS Priority
) p
LEFT JOIN
(
SELECT  Priority, COUNT(*) AS cnt
FROM    jobs
GROUP BY
Priority
) j
ON      j.Priority = p.Priority

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I would need to display the jobid, jobname and 5 fields called Priority1, Priority2, Priority3, Priority4. Priority5.

Something's wrong with your query design. You're showing a specific job in each row as well, and so you'll either have a situation where ever row has four priority columns with a '0' and one priority column with a '1' (the priority for that job) or you'll end up repeating the count for all priorities on every row.

What do you really want to show here?

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Using ANSI SQL-92 CASE Statements, you could do something like this (derived table plus case):

 SELECT jobId, jobName, SUM(Priority1)
AS Priority1, SUM(Priority2) AS
Priority2, SUM(Priority3) AS
Priority3, SUM(Priority4) AS
Priority4,  SUM(Priority5) AS
Priority5 FROM (
SELECT jobId, jobName,
CASE WHEN Priority = 1 THEN 1 ELSE 0 END AS Priority1,
CASE WHEN Priority = 2 THEN 1 ELSE 0 END AS Priority2,
CASE WHEN Priority = 3 THEN 1 ELSE 0 END AS Priority3,
CASE WHEN Priority = 4 THEN 1 ELSE 0 END AS Priority4,
CASE WHEN Priority = 5 THEN 1 ELSE 0 END AS Priority5
FROM TableName




)

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最佳答案

I think you may be after

select
jobID, JobName,
sum(case when Priority = 1 then 1 else 0 end) as priority1,
sum(case when Priority = 2 then 1 else 0 end) as priority2,
sum(case when Priority = 3 then 1 else 0 end) as priority3,
sum(case when Priority = 4 then 1 else 0 end) as priority4,
sum(case when Priority = 5 then 1 else 0 end) as priority5
from
Jobs
group by
jobID, JobName

However I am uncertain if you need to the jobID and JobName in your results if so remove them and remove the group by,

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You could join the table against itself:

select
t.jobId, t.jobName,
count(p1.jobId) as Priority1,
count(p2.jobId) as Priority2,
count(p3.jobId) as Priority3,
count(p4.jobId) as Priority4,
count(p5.jobId) as Priority5
from
theTable t
left join theTable p1 on p1.jobId = t.jobId and p1.jobName = t.jobName and p1.Priority = 1
left join theTable p2 on p2.jobId = t.jobId and p2.jobName = t.jobName and p2.Priority = 2
left join theTable p3 on p3.jobId = t.jobId and p3.jobName = t.jobName and p3.Priority = 3
left join theTable p4 on p4.jobId = t.jobId and p4.jobName = t.jobName and p4.Priority = 4
left join theTable p5 on p5.jobId = t.jobId and p5.jobName = t.jobName and p5.Priority = 5
group by
t.jobId, t.jobName

Or you could use case inside a sum:

select
jobId, jobName,
sum(case Priority when 1 then 1 else 0 end) as Priority1,
sum(case Priority when 2 then 1 else 0 end) as Priority2,
sum(case Priority when 3 then 1 else 0 end) as Priority3,
sum(case Priority when 4 then 1 else 0 end) as Priority4,
sum(case Priority when 5 then 1 else 0 end) as Priority5
from
theTable
group by
jobId, jobName

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Using COUNT instead of SUM removes the requirement for an ELSE statement:

SELECT jobId, jobName,
COUNT(CASE WHEN Priority=1 THEN 1 END) AS Priority1,
COUNT(CASE WHEN Priority=2 THEN 1 END) AS Priority2,
COUNT(CASE WHEN Priority=3 THEN 1 END) AS Priority3,
COUNT(CASE WHEN Priority=4 THEN 1 END) AS Priority4,
COUNT(CASE WHEN Priority=5 THEN 1 END) AS Priority5
FROM TableName
GROUP BY jobId, jobName

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IIF is not a standard SQL construct, but if it's supported by your database, you can achieve a more elegant statement producing the same result:

SELECT JobId, JobName,


COUNT(IIF (Priority=1, 1, NULL)) AS Priority1,
COUNT(IIF (Priority=2, 1, NULL)) AS Priority2,
COUNT(IIF (Priority=3, 1, NULL)) AS Priority3,
COUNT(IIF (Priority=4, 1, NULL)) AS Priority4,
COUNT(IIF (Priority=5, 1, NULL)) AS Priority5


FROM TableName
GROUP BY JobId, JobName

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Try this:

SELECT Count(Student_ID) as 'StudentCount'
FROM CourseSemOne
where Student_ID=3
Having Count(Student_ID) < 6 and Count(Student_ID) > 0;