How do I combine two queries (union all) into one row?

Question

I have a tricky situation in trying to get information from multiple queries into a single row.

Consider the following table:

CpuUage:
    Time    ti         


        

Answer 1

It's a typical pivot query - here's how you'd do it with CASE statements:

  SELECT t.group,
         SUM(CASE 
           WHEN t.subsys = 'NORM' THEN t.jobs 
           ELSE NULL
         END CASE) AS NormJobs,
         SUM(CASE 
           WHEN t.subsys = 'NORM' THEN t.cpu
           ELSE NULL
         END CASE) AS NormCpu,
         SUM(CASE 
           WHEN t.subsys = 'SYS7' THEN t.jobs 
           ELSE NULL
         END CASE) AS Sys7Jobs,
         SUM(CASE 
           WHEN t.subsys = 'SYS7' THEN t.cpu
           ELSE NULL
         END CASE) AS Sys7Cpu
    FROM CPUUSAGE t
GROUP BY t.group

Unfortunately, DB2's CASE statements need to end with END CASE, when Oracle/SQL Server/MySQL/Postgres doesn't. Well, PLSQL supports END CASE...

There's also the PIVOT syntax, which is also supported on Oracle 11g, and SQL Server 2005+.