Informix SQL SELECT 多行結果 - 如何在一行中顯示？

Question

以下請求：

select s.site_name as site, NVL(ct.calltypename,"<No queue assigned>") as queue,
  AVG(TO_NUMBER(cd.datavalue)) as average, count(distinct cr.callid) as count
from callrecord cr 
left join calldata cd on cd.callid=cr.callid and cd.sitekey=cr.arrivalsite and cr.requeuecount=cd.requeuecount-1 
left join calltypes ct on cr.arrivalsite=ct.sitekey and cr.calltypekey=ct.calltypekey
left join sites s on cr.arrivalsite=s.sitekey
where cd.datakey="key1"
group by site, queue

產生以下結果：

  site  queue                   average    count
  MSK     <No queue assigned>   3.00       4
  MSK     Sales                 2.00       1                
  MSK     Service               3.63       32 

結果中最多可能有 6 行。 任務是為使用 SQL 檢索數據的應用程序重新格式化輸出。 此應用程序只能發送一個 SQL 命令，並且只能處理一行。 所以 SQL 結果應該是這樣的：

  site1   queue1   average1   count1   site2   queue2   average2  count2 ...
  MSK     Sales    2.00       1        MSK     Service  3.63      32

每個隊列應該始終出現在同一列中也很重要； 如果沒有數據，列應為空、空或零。 我找到了一些 MS SQL 的示例，但它們在 Informix 中不起作用。

Answer 1

我認為您可以使用窗口函數和條件聚合：

with t as (
      < your query here >
     )
select max(case when seqnum = 1 then site end) as site_1,
       max(case when seqnum = 1 then queue end) as queue_1,
       max(case when seqnum = 1 then average end) as average_1,
       . . . 
       max(case when seqnum = 6 then site end) as site_6,
       max(case when seqnum = 6 then queue end) as queue_6,
       max(case when seqnum = 6 then average end) as average_6,
from (select t.*,
             row_number() over (partition by site order by queue) as seqnum
      from t
     ) t;