甲骨文 12c : Insert into Table with Identity Column

Question

我有一个表，其中有一列类型为标识列，这也是主键。

CREATE  TABLE identity_demo  (
    id NUMBER GENERATED BY DEFAULT ON NULL AS IDENTITY,
    description VARCHAR2(100) not null
  );

然后我插入几行数据

insert into identity_demo (id, description) values (1,'A');
insert into identity_demo (id, description) values (2,'B');
insert into identity_demo (id, description) values (3,'C');
insert into identity_demo (id, description) values (4,'D');
insert into identity_demo (id, description) values (5,'E');
insert into identity_demo (id, description) values (6,'F');

如果我现在想插入未设置值 ID 的行，我会遇到键冲突

insert into identity_demo (description) values ('G');

ORA-00001:唯一约束 (UWE.IDENTITY_DEMO_PK)在这里进行的最佳方式是什么？

Answer 1

首先，似乎有一部分，CONSTRAINT IDENTITY_DEMO_PK PRIMARY KEY (id)

添加到建表DDL的末尾。

只需删除 BY DEFAULT ON NULL 部分，以便将身份生成的管理留给 DBMS，同时将 ID 列保留为 PRIMARY KEY。在这种情况下，您应该从插入语句中的列列表中删除 ID 列，如

INSERT INTO identity_demo (description) VALUES ('G'); :

SQL> CREATE  TABLE identity_demo  (
  2      id          NUMBER GENERATED AS IDENTITY,
  3      description VARCHAR2(100) NOT NULL,
  4      CONSTRAINT IDENTITY_DEMO_PK PRIMARY KEY (id)
  5    );

Table created

SQL> BEGIN
  2    INSERT INTO identity_demo (id, description) VALUES (1,'A');
  3    INSERT INTO identity_demo (id, description) VALUES (2,'B');
  4    INSERT INTO identity_demo (id, description) VALUES (3,'C');
  5    INSERT INTO identity_demo (id, description) VALUES (4,'D');
  6    INSERT INTO identity_demo (id, description) VALUES (5,'E');
  7    INSERT INTO identity_demo (id, description) VALUES (6,'F');
  8  END;
  9  /

ORA-32795: cannot insert into a generated always identity column
ORA-06512: at line 3

SQL> INSERT INTO identity_demo (description) VALUES ('G');

1 row inserted

SQL> SELECT * FROM identity_demo;

        ID DESCRIPTION
---------- -------------------------------------------------------
         1 G

SQL> BEGIN
  2    INSERT INTO identity_demo (description) VALUES ('A');
  3    INSERT INTO identity_demo (description) VALUES ('B');
  4    INSERT INTO identity_demo (description) VALUES ('C');
  5    INSERT INTO identity_demo (description) VALUES ('D');
  6    INSERT INTO identity_demo (description) VALUES ('E');
  7    INSERT INTO identity_demo (description) VALUES ('F');
  8  END;
  9  /

PL/SQL procedure successfully completed

SQL> SELECT * FROM identity_demo;

        ID DESCRIPTION
---------- --------------------------------------------------------
         1 G
         2 A
         3 B
         4 C
         5 D
         6 E
         7 F

7 rows selected