在不存在的地方插入记录

Question

INSERT INTO CUST_ID_HISTORY(CUST_ID,PREVIOUS_CUST_ID,UPDATE_DATE) 
SELECT CUST_ID,PREVIOUS_CUST_ID,UPDATE_DATE
FROM CUST_ID_HISTORY WHERE NOT EXISTS (SELECT 1 FROM CUST_ID_HISTORY WHERE
CUST_ID='SCB301' AND PREVIOUS_CUST_ID='SCB201');

当 table.I 中插入的值不存在时，上述查询向 CUST_ID_HISTORY 插入一条新记录，遇到错误 ORA-00001: unique constraint 中提供的值，但两个值都不存在于 table.I 中table.

Answer 1

您的语句从 CUST_ID_HISTORY 中选择并插入到 CUST_ID_HISTORY 中。换句话说，当 CUST_ID != 'SCB301' 和 PREVIOUS_CUST_ID != 'SCB201' 没有记录时，它会尝试为 CUST_ID_HISTORY 中的每条记录创建一个重复记录。大概这是 table 的主键，因此 ORA-00001 唯一键违规。

如果您想要实现的是将这些值的记录插入 CUST_ID_HISTORY，您可能需要一个合并语句。像这样：

merge into CUST_ID_HISTORY tgt
using ( select 'SCB301' as id, 'SCB201' as prev_id
         from dual ) src
on ( src.id = tgt.cust_id 
      and src.prev_id = tgt.prev_cust_id)
when not matched then
    insert (cust_id, prev_cust_id, update_date)
    values (src.id, src.prev_id, sysdate)
/

Answer 2

查询：

INSERT INTO CUST_ID_HISTORY(CUST_ID,PREVIOUS_CUST_ID,UPDATE_DATE) 
SELECT CUST_ID,PREVIOUS_CUST_ID,UPDATE_DATE
FROM CUST_ID_HISTORY

将复制所有 CUST_ID_HISTORY table 的行。

添加过滤器：

WHERE NOT EXISTS (
  SELECT 1
  FROM CUST_ID_HISTORY
  WHERE CUST_ID='SCB301' AND PREVIOUS_CUST_ID='SCB201'
);

将检查 table 中是否存在现有行 CUST_ID='SCB301' AND PREVIOUS_CUST_ID='SCB201' 如果该行不存在则所有来自 [=14 的行=] table 将被复制，如果存在这样的行，则该语句将插入零行。

所以您的查询要么重复所有行，要么什么都不做。

如果你想插入一个新行，检查它不存在然后：

INSERT INTO CUST_ID_HISTORY(CUST_ID,PREVIOUS_CUST_ID,UPDATE_DATE) 
SELECT 'SCB301',
       'SCB201',
       SYSDATE   -- The current date/time
FROM   DUAL
WHERE NOT EXISTS (
  SELECT 1
  FROM CUST_ID_HISTORY
  WHERE CUST_ID='SCB301' AND PREVIOUS_CUST_ID='SCB201'
);

或：

MERGE INTO CUST_ID_HISTORY dst
USING (
  SELECT 'SCB301' AS CUST_ID,
         'SCB201' AS PREVIOUS_CUST_ID
  FROM   DUAL
) src
ON (   src.CUST_ID          = dst.CUST_ID
   AND src.PREVIOUS_CUST_ID = dst.PREVIOUS_CUST_ID )
WHEN NOT MATCHED THEN
  INSERT ( CUST_ID, PREVIOUS_CUST_ID, UPDATE_DATE ) 
  VALUES ( src.CUST_ID, src.PREVIOUS_CUST_ID, SYSDATE );

这将同时检查是否存在现有行，如果不存在则插入一行。

在不存在的地方插入记录

insert record where not exist

oracle

insert

not-exists

ora-00001