將多行項目分組爲單行

Question

是否有可能得到這樣的結果？

datetime   | sysname | resource | metric  | value 
-------------------+---------+------------+-------------+------- 
Nov 23,2016 2:00 |  A |  A-2 | Utilization | 0.30 
Nov 23,2016 2:00 |  A |  A-2 | Throughput | 300 
Nov 23,2016 2:00 |  B |  B-2 | Utilization | 10.8 
Nov 23,2016 2:00 |  B |  B-2 | Throughput | 1080 

預期輸出：

datetime   | sysname | resource | Utilization | Throughput 
------------------+---------+----------+-------------+------- 
Nov 23,2016 2:00 | A  | A-2  | 0.3  | 300 
Nov 23,2016 2:00 | B  | B-2  | 10.8  | 1080 

Answer 1

SELECT datetime, sysname, resource, a.value, b.value 
FROM metrics a 
    JOIN metrics b 
     USING (datetime, sysname, resource) 
WHERE a.metric = 'Utilization' AND b.metric = 'Throughput';