未找到sql完整性约束父项

我正在尝试做一些非常简单的事情,创建并插入4个表及其数据。我花了几个小时在网上研究完整性约束,并尝试了几个IDE以防出现错误,但似乎什么都不起作用。代码如下所示(按顺序执行)。

我可以插入前两个表的数据,即vod\U actor和vod\U classification,但在尝试添加第三/第四个表数据时,我会遇到以下错误: ORA-02291:违反完整性约束(SYSTEM.VOD\u FILM\u CLASS\u FK)-父级

我不明白为什么,因为FK for vod\u电影是PK for vod\u分类,它已经填充了数据。

任何帮助都将不胜感激。我是初学者,请记住这一点。谢谢

     CREATE TABLE vod_actor (
     dbActorId      CHAR(4) NOT NULL,
     dbFirstname    VARCHAR2(50) NOT NULL,
     dbLastname     VARCHAR2(50) NOT NULL,
     dbDateOfBirth  DATE,
     dbNationality  VARCHAR2(30),
     dbBiography    CLOB,
     CONSTRAINT vod_actor_PK PRIMARY KEY (dbActorId)
     );

     CREATE TABLE vod_classification (
     dbClassId  CHAR(4) NOT NULL,
     dbDescription  VARCHAR(250) NOT NULL,
     CONSTRAINT vod_classification_PK PRIMARY KEY (dbClassId)
     );

     CREATE TABLE vod_film (
     dbFilmId   CHAR(4) NOT NULL,
     dbTitle        VARCHAR2(100) NOT NULL,
     dbDirector_firstname   VARCHAR2(50) NOT NULL,
     dbDirector_lastname    VARCHAR2(50) NOT NULL,
     dbGenre        VARCHAR2(20),
     dbUK_release_date  DATE,
     dbFilename     VARCHAR2(50),
     dbRuntime  NUMBER(4),
     dbClass        CHAR(3),
     CONSTRAINT vod_film_PK PRIMARY KEY (dbFIlmId),
     CONSTRAINT vod_film_class_FK FOREIGN KEY (dbClass) REFERENCES
     vod_classification (dbClassId) ON DELETE SET NULL
     );

     CREATE TABLE vod_role (
     dbFilmId           Char(4) NOT NULL,
     dbActorId          CHAR(4) NOT NULL,
     dbCharacterName    VARCHAR2(25) NOT NULL,
     dbFirstAppearance  NUMBER(6),
     dbDescription      CLOB,
     CONSTRAINT vod_role_PK PRIMARY KEY (dbFilmId, dbActorId, dbCharacterName),
     CONSTRAINT vod_role_film_FK FOREIGN KEY (dbFilmId) REFERENCES vod_film (dbFilmId)
     ON DELETE CASCADE,
     CONSTRAINT vod_role_actor_FK FOREIGN KEY (dbActorId) REFERENCES         vod_actor (dbActorId)
     ON DELETE CASCADE
     );

     //Insert into vod_actor & vod_classification works fine

执行下面的代码会出现错误:

     INSERT INTO vod_film VALUES ('1', 'Toy Story 3', 'Lee', 'Unkrich', 'Comedy', '19-JUL-2010', 'ToyStory3.mpg', '103', 'U');

     INSERT INTO vod_film VALUES ('2', 'Lord of the Rings: Fellowship of the ring', 'Peter', 'Jackson', 'Fantasy', '19-DEC-2001', 'Fellowship.mpg', '178', '12');

     INSERT INTO vod_film VALUES ('3', 'Lord of the Rings: Two Towers', 'Peter', 'Jackson', 'Fantasy', '18-DEC-2002', 'TwoTowers.mpg', '179', '12');

     INSERT INTO vod_film VALUES ('4', 'Lord of the Rings: Return of the King', 'Peter', 'Jackson', 'Fantasy', '17-DEC-2003', 'KingReturns.mpg', '201', '12');

     INSERT INTO vod_film VALUES ('5', 'Face/Off', 'John', 'Woo', 'Action', '7-NOV-1997', 'FaceOff.mpg', '138', '18');

     INSERT INTO vod_film VALUES ('6', 'The Nutty Professor', 'Tom', 'Shadyac', 'Comedy', '4-OCT-1996', 'NuttyProf.mpg', '95', '12');