Oracle - 重写此查询以不使用子选择的方法？

Question

我试图在Oracle 11.1中创建物化视图，这显然不支持物化视图中的嵌套选择（为什么这是，我一直无法弄清楚）..有没有办法写这个查询作为物化视图工作？谢谢！

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); 

我得到的错误是：

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

Answer 1

尝试以下查询：

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

我认为这是一个限制（即从小就是一个错误的某个时候回来），在这里记录了甲骨文网站上 - http://download.oracle.com/docs/cd/B12037_01/server.101/b10736/basicmv.htm#sthref431

要解决，你应该使用JOINS而不是子查询。