Oracle - 重寫此查詢以不使用子選擇的方法？

Question

我試圖在Oracle 11.1中創建物化視圖，這顯然不支持物化視圖中的嵌套選擇（爲什麼這是，我一直無法弄清楚）..有沒有辦法寫這個查詢作爲物化視圖工作？謝謝！

CREATE MATERIALIZED VIEW MV_Area90DayReport 
    NOLOGGING 
    CACHE 
    BUILD IMMEDIATE 
    REFRESH FAST ON COMMIT 
    AS 
    select 
     T.TASKID, 
     V.PROJECTID, 
     V.VERSIONID, 
     T.GOLDDATE, 
     P.BUSINESSLAUNCHDATE, 
     V.NAME as ProjectName, 
     T.NAME as TaskName, 
     T.COURSECODE, 
     DT.NAME as DeliveryMethod, 
     T.DELIVERABLELENGTHHOUR, 
     T.DELIVERABLELENGTHMINUTE, 
     V.PRIORITY, 
     (SELECT MIN(STARTDATE) FROM TPM_TRAININGPLAN WHERE PROJECTID=V.PROJECTID AND TRAININGPLANTYPE='prescribed') as TrainingDeliveryDate, 
     (SELECT wm_concat(WORKGROUPID) FROM TPM_PROJECTWORKGROUPS WHERE PROJECTID=V.PROJECTID GROUP BY PROJECTID) as Workgroups, 
    from TPM_TASK T 
    inner join TPM_PROJECTVERSION V ON (V.PROJECTID = T.PROJECTID AND V.VERSIONID = T.VERSIONID) 
    inner join TPM_PROJECT P ON (P.PROJECTID = T.PROJECTID) 
    inner join TPM_DOCUMENTTYPE DT ON (DT.DOCUMENTTYPEID = T.DOCUMENTTYPEID); 

我得到的錯誤是：

>[Error] Script lines: 1-25 ------------------------- 
ORA-22818: subquery expressions not allowed here 
Script line 20, statement line 20, column 115 

Answer 1

嘗試以下查詢：

select 
    T.TASKID, 
    V.PROJECTID, 
    V.VERSIONID, 
    T.GOLDDATE, 
    P.BUSINESSLAUNCHDATE, 
    V.NAME as ProjectName, 
    T.NAME as TaskName, 
    T.COURSECODE, 
    DT.NAME as DeliveryMethod, 
    T.DELIVERABLELENGTHHOUR, 
    T.DELIVERABLELENGTHMINUTE, 
    V.PRIORITY, 
    TP.TrainingDeliveryDate, 
    WG.Workgroups, 
from TPM_TASK T 
inner join TPM_PROJECTVERSION V ON (V.PROJECTID = T.PROJECTID AND V.VERSIONID = T.VERSIONID) 
inner join TPM_PROJECT P ON (P.PROJECTID = T.PROJECTID) 
inner join TPM_DOCUMENTTYPE DT ON (DT.DOCUMENTTYPEID = T.DOCUMENTTYPEID) 
left join (
    SELECT PROJECTID, MIN(STARTDATE) as TrainingDeliveryDate 
    FROM TPM_TRAININGPLAN 
    WHERE TRAININGPLANTYPE='prescribed' 
    GROUP BY PROJECTID 
) TP on TP.PROJECTID=V.PROJECTID 
left join (
    SELECT PROJECTID, wm_concat(WORKGROUPID) as Workgroups 
    FROM TPM_PROJECTWORKGROUPS 
    GROUP BY PROJECTID 
) WG on WG.PROJECTID=V.PROJECTID 

Answer 2

我認爲這是一個限制（即從小就是一個錯誤的某個時候回來），在這裏記錄了甲骨文網站上 - http://download.oracle.com/docs/cd/B12037_01/server.101/b10736/basicmv.htm#sthref431

要解決，你應該使用JOINS而不是子查詢。