添加外键约束时遇到问题（错误 ORA-02270：此列列表没有匹配的唯一键或主键）

Question

我正在学习如何为具有主键和外键限制的班级创建一个小而简单的数据库。我在尝试运行我的 ALTER TABLE 语句时收到 ORA-02770，据我了解，这是通知我在外部表中引用的列未列为主键约束。但是，据我所知，我的语法在 CREATE TABLES 语句中命名主键是正确的。我在 all_cons_columns 表中搜索了 player_info 表，它也显示了列出的主键。我能得到一些指导吗？下面列出的是我当前的脚本：

CREATE TABLE Player_Game
( school varchar2(30),
  player_number number(2,0),
  game_number number(1,0), 

  CONSTRAINT playergame_pk PRIMARY KEY (school, player_number,game_number)
);

CREATE TABLE School 
( school varchar2(30), 
  city varchar2(30), 
  coach varchar2(30), 
  team_name varchar2(30),
  win_record number (2,0), 
  loss_record number (2,0), 

  CONSTRAINT school_pk PRIMARY KEY (school)
);

CREATE TABLE Game 
( school varchar2(30),
  game_number number(1,0), 
  game_date DATE, 
  game_score varchar2(15), 

  CONSTRAINT game_pk PRIMARY KEY (school, game_number)
);

CREATE TABLE player_info
( school varchar2(30), 
  player_number number(2,0), 
  player_name varchar2(25), 

 CONSTRAINT playerinfo_pk PRIMARY KEY (school, player_number)
);

CREATE TABLE city 
( city varchar2(30),
  population number(5,0),

 CONSTRAINT city_pk PRIMARY KEY (city)
);

/*Here is the failing alter command */
ALTER TABLE Player_Game
ADD CONSTRAINT playergame_fk FOREIGN KEY (school) REFERENCES game(school); 

Answer 1

您在 alter table 语句中的 playergame_fk 中有不正确的列列表。 外键的列列表必须与它所引用的主键的列列表完全匹配。

主键列列表为school, game_number，因此，您的外键必须具有相同的列：

ALTER TABLE Player_Game
ADD CONSTRAINT playergame_fk FOREIGN KEY (school, game_number) 
  REFERENCES game(school, game_number);