Sql 自引用表上的合并约束错误

MERGE正在引发一个错误

ORA-02291: integrity constraint violated-parent key not found

插入到自引用表中时。 如果我用“无所谓”稍微更改一下查询，它就会工作

MERGE INTO TRG t USING(
  SELECT ID, PARENT FROM SRC
) s ON (t.ID=s.ID)
WHEN NOT MATCHED THEN INSERT(ID,PARENT) VALUES (s.ID,s.PARENT);

DROP TABLE SRC;
CREATE TABLE SRC (
  ID NUMBER PRIMARY KEY,
  PARENT NUMBER
);

INSERT INTO SRC SELECT 1, null FROM DUAL;
INSERT INTO SRC SELECT 2, 1 FROM DUAL;

DROP TABLE TRG;
CREATE TABLE TRG (
  ID NUMBER PRIMARY KEY,
  PARENT NUMBER,
  CONSTRAINT FK2 FOREIGN KEY(PARENT) REFERENCES TRG(ID)
);

MERGE INTO TRG t USING(
  SELECT PARENT, ID FROM SRC
) s ON (t.ID=s.ID)
WHEN NOT MATCHED THEN INSERT(ID,PARENT) VALUES (s.ID,s.PARENT);

我做错什么了吗

执行命令：

准备材料

第一个合并查询（不起作用）

第二个合并查询（将起作用）

合并查询中列的顺序并不重要。您还可以在第一次合并之前运行第二次合并

如果要重新启动测试，请从DROP TABLE TGR开始

首先是一些准备工作：

DROP TABLE SRC;
CREATE TABLE SRC (
  ID VARCHAR(20) PRIMARY KEY,
  PARENT VARCHAR(20)
);

INSERT INTO SRC SELECT '1', null FROM DUAL;
INSERT INTO SRC SELECT '2', '1' FROM DUAL;

DROP TABLE TRG;
CREATE TABLE TRG (
  ID VARCHAR(20) PRIMARY KEY,
  PARENT VARCHAR(20),
  CONSTRAINT FK2 FOREIGN KEY(PARENT) REFERENCES TRG(ID)
);

这是行不通的：

MERGE INTO TRG t USING(
  SELECT PARENT, ID FROM SRC
) s ON (t.ID=s.ID)
WHEN NOT MATCHED THEN INSERT(ID,PARENT) VALUES (s.ID,s.PARENT);

但这是可行的

MERGE INTO TRG t USING(
  SELECT ID, PARENT FROM SRC
) s ON (t.ID=s.ID)
WHEN NOT MATCHED THEN INSERT(ID,PARENT) VALUES (s.ID,s.PARENT);

DROP TABLE SRC;
CREATE TABLE SRC (
  ID NUMBER PRIMARY KEY,
  PARENT NUMBER
);

INSERT INTO SRC SELECT 1, null FROM DUAL;
INSERT INTO SRC SELECT 2, 1 FROM DUAL;

DROP TABLE TRG;
CREATE TABLE TRG (
  ID NUMBER PRIMARY KEY,
  PARENT NUMBER,
  CONSTRAINT FK2 FOREIGN KEY(PARENT) REFERENCES TRG(ID)
);

MERGE INTO TRG t USING(
  SELECT PARENT, ID FROM SRC
) s ON (t.ID=s.ID)
WHEN NOT MATCHED THEN INSERT(ID,PARENT) VALUES (s.ID,s.PARENT);

如果您将这些列的数据类型更改为NUMBER，它将起作用

MERGE INTO TRG t USING(
  SELECT ID, PARENT FROM SRC
) s ON (t.ID=s.ID)
WHEN NOT MATCHED THEN INSERT(ID,PARENT) VALUES (s.ID,s.PARENT);

DROP TABLE SRC;
CREATE TABLE SRC (
  ID NUMBER PRIMARY KEY,
  PARENT NUMBER
);

INSERT INTO SRC SELECT 1, null FROM DUAL;
INSERT INTO SRC SELECT 2, 1 FROM DUAL;

DROP TABLE TRG;
CREATE TABLE TRG (
  ID NUMBER PRIMARY KEY,
  PARENT NUMBER,
  CONSTRAINT FK2 FOREIGN KEY(PARENT) REFERENCES TRG(ID)
);

MERGE INTO TRG t USING(
  SELECT PARENT, ID FROM SRC
) s ON (t.ID=s.ID)
WHEN NOT MATCHED THEN INSERT(ID,PARENT) VALUES (s.ID,s.PARENT);

编辑：

---

忘了告诉：我正在使用12c

您是否尝试过在合并查询中首先对数据进行排序

select parent，id from src order by parent

我在Oracle11g上试过，也在Oracle11g上试过，效果很好。所以这在12c中应该是个问题。在帖子中添加了此提示。问题是为什么我需要运行两次。在OraDocs中，他们说约束将在MERGE语句之后被检查。