Question

我想在Case语句中使用以下语法中的Month Column。当我创建一个子查询时，我收到查询块中所需的Oracle错误01788 Connect By Clause。如何在子查询的案例陈述中使用月份列？

TO_CHAR(ADD_MONTHS(TRUNC(StartDate, 'MM'), LEVEL - 1), 'YYYYMM') AS Month

以下查询：

    SELECT 
CASE 
  WHEN  first_assgn_dt_YYYYMM <= Month 
   THEN 0
  WHEN EndDate < LAST_DAY(EndDate) AND EndDate != sysdate 
 AND LEVEL = 1 + MONTHS_BETWEEN(TRUNC(EndDate,'MM'),TRUNC(StartDate,'MM'))
  THEN 0 
    ELSE 1 
      END AS active_at_month_end 

        FROM (
WITH
     ActiveMemberData (ID,StartDate,EndDate,first_assgn_dt,first_assgn_dt_YYYYMM) AS (
       SELECT DISTINCT 
       x.ID,
       TRUNC(x.start_dt) AS StartDate,
       CASE WHEN TRUNC(X.END_DT) = '1-JAN-3000' THEN SYSDATE ELSE TO_DATE(X.END_DT) END AS EndDate,
       x.first_assgn_dt,
       TO_CHAR(first_assgn_dt,'YYYYMM') AS first_assgn_dt_YYYYMM

FROM X
LEFT JOIN  D ON X.MID = D.ID  

WHERE 1=1

                               )                                   
--------------------------------------------------                                       
   SELECT DISTINCT 
ID,
first_assgn_dt,
first_assgn_dt_YYYYMM,
StartDate,
TO_CHAR(StartDate,'YYYYMM') AS StartDate_YYYYMM, 
EndDate,
TO_CHAR(ADD_MONTHS(TRUNC(StartDate, 'MM'), LEVEL - 1), 'YYYYMM') AS Month,
LAST_DAY(EndDate) AS LastDayOfMonth

FROM  ActiveMemberData

WHERE 1=1
------------------------------------------------------------------------------------
CONNECT BY LEVEL <= 1 + MONTHS_BETWEEN(TRUNC(EndDate,'MM'), TRUNC(StartDate,'MM'))
  AND PRIOR ID = ID AND PRIOR STARTDATE = STARTDATE
  AND PRIOR sys_guid() IS NOT NULL          
                       ) Z
WHERE 1=1

ORDER BY
ID, 
Month

Answer 1

这与尝试从内联视图中引用Month无关;那样就好。它是导致错误的level的单独引用。

如果您希望能够在外部查询中看到内联视图中的level，就像使用此行一样：

 AND LEVEL = 1 + MONTHS_BETWEEN(TRUNC(EndDate,'MM'),TRUNC(StartDate,'MM'))

然后你必须将它包含在选择列表中 - 使用别名 - 然后引用该别名：

SELECT 
CASE 
...
 AND LEVEL_ALIAS = 1 + MONTHS_BETWEEN(TRUNC(EndDate,'MM'),TRUNC(StartDate,'MM'))
...
FROM (
...
   SELECT DISTINCT 
     LEVEL as LEVEL_ALIAS,
     ID,
...

当然，您可以随意调用别名;你不能使用保留字level。

您希望在外部查询中看到的任何内容始终必须位于内联视图的选择列表中 - 但通常您可以保留原始列名称;你必须使用表达式或pseucocolumn的别名，这就是这种情况。

Answer 2

您不必使用保留字的别名。只需添加双引号并将其标题化，即＆＃34; LEVEL＆＃34;

Oracle - 按条件连接查询块中必需的

2 个答案: