Postgres：使用Case和Group By時需要的聚合函數，但僅在使用連接時

Question

我遇到了一個postgres查詢的奇怪問題。除了一個非常特定的場景外，查詢可以在多種情況下使用各種其他分組，總和等方式正常工作。

下面的代碼是從5個不同的表中計算行（忽略這個事實本身是愚蠢的，它是一個非常糟糕和令人討厭的數據庫結構），並根據CASE函數中返回的值對它們進行分組。它正常工作時，它是如下：

SELECT SUM(count) as count, status FROM 
(SELECT count(fsp.id) as count, CASE WHEN fsp.stageonecompletetime = 0 THEN 'in-progress' 
WHEN fsp.stagetwocompletetime = 0 THEN 'awaiting-final-review' 
WHEN fsp.completedtime = 0 THEN 'awaiting-authorisation' 
WHEN fsp.senttodate = 0 THEN 'awaiting-distribution' 
WHEN fsp.senttodate > 0 AND superseded = 0 THEN 'completed' 
ELSE 'archived' END AS status FROM fleet_documents.fleet_solution_policy fsp WHERE TO_TIMESTAMP(fsp.createdtime) >= '2016-09-03' AND TO_TIMESTAMP(fsp.createdtime) < '2016-10-03' GROUP BY status 
UNION ALL 
SELECT count(cba.id) as count, CASE WHEN cba.stageonecompletetime = 0 THEN 'in-progress' 
WHEN cba.stagetwocompletetime = 0 THEN 'awaiting-final-review' 
WHEN cba.completedtime = 0 THEN 'awaiting-authorisation' 
WHEN cba.senttodate = 0 THEN 'awaiting-distribution' 
WHEN cba.senttodate > 0 AND superseded = 0 THEN 'completed' 
ELSE 'archived' END AS status FROM fleet_documents.casing_buyback_agreement cba WHERE TO_TIMESTAMP(cba.createdtime) >= '2016-09-03' AND TO_TIMESTAMP(cba.createdtime) < '2016-10-03' GROUP BY status 
UNION ALL 
SELECT count(ftp.id) as count, CASE WHEN ftp.stageonecompletetime = 0 THEN 'in-progress' 
WHEN ftp.stagetwocompletetime = 0 THEN 'awaiting-final-review' 
WHEN ftp.completedtime = 0 THEN 'awaiting-authorisation' 
WHEN ftp.senttodate = 0 THEN 'awaiting-distribution' 
WHEN ftp.senttodate > 0 AND superseded = 0 THEN 'completed' 
ELSE 'archived' END AS status FROM fleet_documents.fleet_tyre_policy ftp WHERE TO_TIMESTAMP(ftp.createdtime) >= '2016-09-03' AND TO_TIMESTAMP(ftp.createdtime) < '2016-10-03' GROUP BY status 
UNION ALL 
SELECT count(ds.id) as count, CASE WHEN ds.stageonecompletetime = 0 THEN 'in-progress' 
WHEN ds.stagetwocompletetime = 0 THEN 'awaiting-final-review' 
WHEN ds.completedtime = 0 THEN 'awaiting-authorisation' 
WHEN ds.senttodate = 0 THEN 'awaiting-distribution' 
WHEN ds.senttodate > 0 AND superseded = 0 THEN 'completed' 
ELSE 'archived' END AS status FROM fleet_documents.dealer_sla ds WHERE TO_TIMESTAMP(ds.createdtime) >= '2016-09-03' AND TO_TIMESTAMP(ds.createdtime) < '2016-10-03' GROUP BY status 
UNION ALL 
SELECT count(cg.id) as count, CASE WHEN cg.stageonecompletetime = 0 THEN 'in-progress' 
WHEN cg.stagetwocompletetime = 0 THEN 'awaiting-final-review' 
WHEN cg.completedtime = 0 THEN 'awaiting-authorisation' 
WHEN cg.senttodate = 0 THEN 'awaiting-distribution' 
WHEN cg.senttodate > 0 AND superseded = 0 THEN 'completed' 
ELSE 'archived' END AS status FROM fleet_documents.casing_grid cg WHERE TO_TIMESTAMP(cg.createdtime) >= '2016-09-03' AND TO_TIMESTAMP(cg.createdtime) < '2016-10-03' GROUP BY status) allDocuments 
GROUP BY status 

但是，當我必須做在查詢連接，讓我通過用戶過濾結果，如下我得到一個惱人的錯誤：

SELECT SUM(count) as count, status FROM 
    (SELECT count(fsp.id) as count, CASE WHEN fsp.stageonecompletetime = 0 THEN 'in-progress' 
     WHEN fsp.stagetwocompletetime = 0 THEN 'awaiting-final-review' 
     WHEN fsp.completedtime = 0 THEN 'awaiting-authorisation' 
     WHEN fsp.senttodate = 0 THEN 'awaiting-distribution' 
     WHEN fsp.senttodate > 0 AND superseded = 0 THEN 'completed' 
     ELSE 'archived' END AS status FROM fleet_documents.fleet_solution_policy fsp JOIN users u1 ON u1.id = fsp.user_id WHERE TO_TIMESTAMP(fsp.createdtime) >= '2016-09-03' AND TO_TIMESTAMP(fsp.createdtime) < '2016-10-03' AND lower(u1.username) = 'Test' GROUP BY status 
    UNION ALL 
    SELECT count(cba.id) as count, CASE WHEN cba.stageonecompletetime = 0 THEN 'in-progress' 
     WHEN cba.stagetwocompletetime = 0 THEN 'awaiting-final-review' 
     WHEN cba.completedtime = 0 THEN 'awaiting-authorisation' 
     WHEN cba.senttodate = 0 THEN 'awaiting-distribution' 
     WHEN cba.senttodate > 0 AND superseded = 0 THEN 'completed' 
     ELSE 'archived' END AS status FROM fleet_documents.casing_buyback_agreement cba JOIN users u4 ON u4.id = cba.user_id WHERE TO_TIMESTAMP(cba.createdtime) >= '2016-09-03' AND TO_TIMESTAMP(cba.createdtime) < '2016-10-03' AND lower(u4.username) = 'Test' GROUP BY status 
    UNION ALL 
    SELECT count(ftp.id) as count, CASE WHEN ftp.stageonecompletetime = 0 THEN 'in-progress' 
     WHEN ftp.stagetwocompletetime = 0 THEN 'awaiting-final-review' 
     WHEN ftp.completedtime = 0 THEN 'awaiting-authorisation' 
     WHEN ftp.senttodate = 0 THEN 'awaiting-distribution' 
     WHEN ftp.senttodate > 0 AND superseded = 0 THEN 'completed' 
     ELSE 'archived' END AS status FROM fleet_documents.fleet_tyre_policy ftp JOIN users u2 ON u2.id = ftp.user_id WHERE TO_TIMESTAMP(ftp.createdtime) >= '2016-09-03' AND TO_TIMESTAMP(ftp.createdtime) < '2016-10-03' AND lower(u2.username) = 'Test' GROUP BY status 
    UNION ALL 
    SELECT count(ds.id) as count, CASE WHEN ds.stageonecompletetime = 0 THEN 'in-progress' 
     WHEN ds.stagetwocompletetime = 0 THEN 'awaiting-final-review' 
     WHEN ds.completedtime = 0 THEN 'awaiting-authorisation' 
     WHEN ds.senttodate = 0 THEN 'awaiting-distribution' 
     WHEN ds.senttodate > 0 AND superseded = 0 THEN 'completed' 
     ELSE 'archived' END AS status FROM fleet_documents.dealer_sla ds JOIN users u3 ON u3.id = ds.user_id WHERE TO_TIMESTAMP(ds.createdtime) >= '2016-09-03' AND TO_TIMESTAMP(ds.createdtime) < '2016-10-03' AND lower(u3.username) = 'Test' GROUP BY status 
    UNION ALL 
    SELECT count(cg.id) as count, CASE WHEN cg.stageonecompletetime = 0 THEN 'in-progress' 
     WHEN cg.stagetwocompletetime = 0 THEN 'awaiting-final-review' 
     WHEN cg.completedtime = 0 THEN 'awaiting-authorisation' 
     WHEN cg.senttodate = 0 THEN 'awaiting-distribution' 
     WHEN cg.senttodate > 0 AND superseded = 0 THEN 'completed' 
     ELSE 'archived' END AS status FROM fleet_documents.casing_grid cg JOIN users u5 ON u5.id = cg.user_id WHERE TO_TIMESTAMP(cg.createdtime) >= '2016-09-03' AND TO_TIMESTAMP(cg.createdtime) < '2016-10-03' AND lower(u5.username) = 'Test' GROUP BY status) allDocuments 
GROUP BY status 

我得到的錯誤如下：錯誤：列「fsp.stageonecompletetime」必須出現在GROUP BY子句中或用於聚合函數中。

現在，我不明白爲什麼我得到這個錯誤，只有當我與用戶表進行連接時才返回。

任何幫助將不勝感激。

Answer 1

我懷疑你的users表中有一個名爲status的列，這已經改變了組的語義，所以它不再引用別名的case表達式。

嘗試更改您使用的別名。

Answer 2

這不是真正的答案。 David Aldridge已經給出了正確的答案。

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這裏是我將如何寫查詢。我根本不會加入用戶。我會先把所有的桌子粘在一起，然後和他們一起工作，就好像他們只是一張桌子一樣。我將數據分類到子查詢中，然後在主查詢中使用創建的別名。

select count(*), status 
from 
(
    select 
    case 
     when stageonecompletetime = 0 then 'in-progress' 
     when stagetwocompletetime = 0 then 'awaiting-final-review' 
     when completedtime = 0 then 'awaiting-authorisation' 
     when senttodate = 0 then 'awaiting-distribution' 
     when senttodate > 0 and superseded = 0 then 'completed' 
     else 'archived' 
    end as status 
    from 
    (
    select user_id, createdtime, stageonecompletetime, stagetwocompletetime, completedtime, senttodate, superseded from fleet_documents.fleet_solution_policy 
    union all 
    select user_id, createdtime, stageonecompletetime, stagetwocompletetime, completedtime, senttodate, superseded from fleet_documents.casing_buyback_agreement 
    union all 
    select user_id, createdtime, stageonecompletetime, stagetwocompletetime, completedtime, senttodate, superseded from fleet_documents.fleet_tyre_policy 
    union all 
    select user_id, createdtime, stageonecompletetime, stagetwocompletetime, completedtime, senttodate, superseded from fleet_documents.dealer_sla 
    union all 
    select user_id, createdtime, stageonecompletetime, stagetwocompletetime, completedtime, senttodate, superseded from fleet_documents.casing_grid 
) data 
) classified 
where createdtime >= '2016-09-03' 
    and createdtime < '2016-10-03' 
    and user_id in (select id from users where lower(username) = 'test') 
group by status 
order by count(*); 

只有當速度太慢時，纔會將WHERE子句移到單表查詢中。正如查詢更具可讀性和可維護性。