Question

SELECT cust_detl.*, 
       MIN(CREATION_TIMESTAMP) OVER (PARTITION BY CUST_ID) AS MIN_TIMESTAMP
FROM CUST_DETAILS cust_detl
WHERE CREATION_TIMESTAMP=MIN_TIMESTAMP;

以上查询选择表CUST_DETAILS中CREATION_TIMESTAMP列中包含最旧值的所有列。

知道为什么MIN_TIMESTAMP会遇到无效的标识符？

这些是应显示的列：

SELECT
  CUSTOMER_DTL_SEQ.nextval,
  CUST_ID
  CUS_REF_ID
  CUST_NAME
  CUST_ADDRESS
  CREATION_TIMESTAMP
FROM
(
  CUSTOMER_DTL_SEQ.nextval,
   cust_detl.CUST_ID,
   cust_detl.CUST_REF_ID,
   cust_detl.CUST_NAME,
   cust_detl.CUST_ADDRESS,
   cust_detl.CREATION_TIMESTAMP,
    MIN(CREATION_TIMESTAMP) OVER (PARTITION BY CUST_ID) AS min_timestamp
    FROM cust_details cust_detl
  )
 WHERE CREATION_TIMESTAMP = min_timestamp;

我还需要选择CREATION_TIMESTAMP列，只会选择那些时间戳最小的列。问题是不允许使用nextval的序列。我需要在查询中使用序列，因为此语句稍后会用于INSERT SELECT...INSERT INTO

PK需要递增。

Answer 1

列名尚未生效，首先使用where条件过滤数据，然后在过滤后的数据上过滤，select语句有效。您需要先将其放在子查询中才能使用它。

SELECT * FROM
(SELECT cust_detl.*, 
        MIN(CREATION_TIMESTAMP) OVER (PARTITION BY CUST_ID) AS MIN_TIMESTAMP
   FROM CUST_DETAILS cust_detl)
WHERE CREATION_TIMESTAMP=MIN_TIMESTAMP;

更新：我不知道您的表中有哪些列列表，但如果您只需要特定列，那么查询就是这样（假设您只需要列cust_id，column1 ，选择列表中的column2和column3）

SELECT cust_id,
       column1,
       column2,
       column3
  FROM (SELECT cust_detl.cust_id,
               cust_detl.column1,
               cust_detl.column2,
               cust_detl.column3,
               cust_detl.creation_timestamp,
               MIN(creation_timestamp) over(PARTITION BY cust_id) AS min_timestamp
          FROM cust_details cust_detl)
 WHERE creation_timestamp = min_timestamp;

如果您仍然没有得到解决方案，请发布表格中的列列表和预期的输出。

Update2 ：在外部查询中获取光标，此查询应该可以正常工作。

SELECT customer_dtl_seq.nextval,
       cust_id,
       cus_ref_id, 
       cust_name,
       cust_address,
       creation_timestamp
  FROM (SELECT cust_detl.cust_id,
               cust_detl.cust_ref_id,
               cust_detl.cust_name,
               cust_detl.cust_address,
               cust_detl.creation_timestamp,
               MIN(creation_timestamp) over(PARTITION BY cust_id) AS min_timestamp
          FROM cust_details cust_detl)
 WHERE creation_timestamp = min_timestamp;

作为聚合函数MIN（）的结果后，列名变为无效

1 个答案: