当ora_rowscn在USING子句中时,Oracle Merge语句行为

Question

我有一个MERGE语句,它给了我可怕的ORA-00904: invalid identifier错误消息.请注意,此处不存在"无效标识符"错误的典型问题 - 我没有尝试更新已加入的列,也没有拼错我的列名.我正在尝试使用Oracle伪列ORA_ROWSCN在USING条款的SELECT说法.

使用这些示例表,我尝试运行

MERGE INTO MY_MERGE_TABLE D
  USING
 (SELECT PRIMARY_KEY, 
         COALESCE (UPDATE_DT, CREATED_DT) update_dt,
         ORA_ROWSCN AS rowscn 
    FROM MY_SOURCE_TABLE) S
   ON (D.PRIMARY_KEY = S.PRIMARY_KEY)
WHEN MATCHED THEN
     UPDATE SET D.update_dt = GREATEST(D.update_dt, S.update_dt),
                D.rowscn = GREATEST(D.rowscn, S.rowscn)
WHEN NOT MATCHED THEN
     INSERT (D.PRIMARY_KEY, D.UPDATE_DT, D.ROWSCN)
     VALUES (S.PRIMARY_KEY, S.UPDATE_DT, S.ROWSCN);

如果我从USING子句中删除伪列ora_rowscn,我不再收到错误消息,并且合并成功完成.

MERGE INTO MY_MERGE_TABLE D
  USING
 (SELECT PRIMARY_KEY, 
         COALESCE (UPDATE_DT, CREATED_DT) update_dt
    FROM MY_SOURCE_TABLE) S
   ON (D.PRIMARY_KEY = S.PRIMARY_KEY)
WHEN MATCHED THEN
     UPDATE SET D.update_dt = GREATEST(D.update_dt, S.update_dt)
WHEN NOT MATCHED THEN
     INSERT (D.PRIMARY_KEY, D.UPDATE_DT)
     VALUES (S.PRIMARY_KEY, S.UPDATE_DT);

如果我将查询放入VIEW,我可以成功使用ora_rowscn:

CREATE VIEW MY_VIEW AS 
    SELECT PRIMARY_KEY, 
         COALESCE (UPDATE_DT, CREATED_DT) update_dt,
         ORA_ROWSCN AS rowscn 
    FROM MY_SOURCE_TABLE;

MERGE INTO MY_MERGE_TABLE D
  USING (SELECT PRIMARY_KEY, UPDATE_DT, ROWSCN FROM MY_VIEW) S
   ON (D.PRIMARY_KEY = S.PRIMARY_KEY)
WHEN MATCHED THEN
     UPDATE SET D.update_dt = GREATEST(D.update_dt, S.update_dt),
                D.rowscn = GREATEST(D.rowscn, S.rowscn)
WHEN NOT MATCHED THEN
     INSERT (D.PRIMARY_KEY, D.UPDATE_DT, D.ROWSCN)
     VALUES (S.PRIMARY_KEY, S.UPDATE_DT, S.ROWSCN);

如果没有为查询创建VIEW,有没有办法做到这一点？作为ETL过程的一部分,我必须在许多表上执行此操作,并且不希望构建多个视图.

编辑:根据Glenn在评论中的建议,我尝试将查询放入子查询中:

MERGE INTO MY_MERGE_TABLE D
  USING
 (WITH QRY AS 
  (SELECT PRIMARY_KEY, 
         COALESCE (UPDATE_DT, CREATED_DT) update_dt,
         ORA_ROWSCN AS rowscn 
    FROM MY_SOURCE_TABLE)
  SELECT ORDER_ID, UPDATE_DT, ROWSCN FROM QRY)
 ON (D.PRIMARY_KEY = S.PRIMARY_KEY)
WHEN MATCHED THEN
     UPDATE SET D.update_dt = GREATEST(D.update_dt, S.update_dt),
                D.rowscn = GREATEST(D.rowscn, S.rowscn)
WHEN NOT MATCHED THEN
     INSERT (D.PRIMARY_KEY, D.UPDATE_DT, D.ROWSCN)
     VALUES (S.PRIMARY_KEY, S.UPDATE_DT, S.ROWSCN);

此查询仍然给出了ORA-00904: invalid identifier错误消息.

这是重新创建问题的DDL.

CREATE TABLE MY_SOURCE_TABLE (
  PRIMARY_KEY NUMBER,
  CREATED_DT TIMESTAMP(6),
  UPDATED_DT TIMESTAMP(6)
);

CREATE TABLE MY_MERGE_TABLE (
  PRIMARY_KEY NUMBER,
  UPDATED_DT TIMESTAMP(6),
  ROWSCN NUMBER
);

INSERT INTO MY_SOURCE_TABLE (PRIMARY_KEY, CREATED_DT, UPDATED_DT)
VALUES (1, SYSDATE-2, SYSDATE);

INSERT INTO MY_SOURCE_TABLE (PRIMARY_KEY, CREATED_DT, UPDATED_DT)
VALUES (2, SYSDATE-1, NULL);

INSERT INTO MY_SOURCE_TABLE (PRIMARY_KEY, CREATED_DT, UPDATED_DT)
VALUES (3, SYSDATE-1, SYSDATE+1);

INSERT INTO MY_MERGE_TABLE (PRIMARY_KEY, UPDATED_DT, ROWSCN)
VALUES (1, SYSDATE-2, 0);

INSERT INTO MY_MERGE_TABLE (PRIMARY_KEY, UPDATED_DT, ROWSCN)
VALUES (2, SYSDATE-1, 0);

Answer 1

我运行你的SQL并得到了同样的错误(在11.2.0.1上).然后我试着运行选择

SELECT PRIMARY_KEY, 
         COALESCE (UPDATE_DT, CREATED_DT) update_dt,
         ORA_ROWSCN AS rowscn 
    FROM MY_SOURCE_TABLE;

仍然有ORA-00904: "UPDATE_DT": invalid identifier错误.然后我注意到在你的DDL中,MY_SOURCE_TABLE调用了列UPDATED_DT(即带有一个额外的D字符).更改对MERGE语句中的引用使它对我有用,希望有所帮助.