Conditional Count on a field

Question

If I had a table like this:

jobId, jobName, Priority

Whereby Priority can be an integer between 1 to 5.

Since I would need this que

Answer 1

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

Answer 2

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


)

Answer 3

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

Answer 4

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

Answer 5

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?

Answer 6

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