正在创建2个表-ORA-00904:：标识符无效

Question

我正在尝试创建两个表：Person和Friend。

在朋友表中，我有一个复合主外键，它引用了Person表中的人身份。

请注意，我试图在Java（Eclipse IDE）中执行此操作。

我一直得到这个错误，当我试图创建的朋友表出于某种原因：

ORA-00904:：标识符无效

  String createPersonalInformationTable = 
              "CREATE TABLE Persons("
            + "personId         INT NOT NULL, "
            + "email_userName   VARCHAR2(50) NOT NULL, "
            + "password         VARCHAR2(50) NOT NULL, "
            + "firstName        VARCHAR2(50) NOT NULL, "
            + "midlleName       VARCHAR2(50), "
            + "lastName         VARCHAR2(50) NOT NULL, "
            + "country          VARCHAR2(50) NOT NULL, "
            + "city             VARCHAR2(50) NOT NULL, "
            + "PRIMARY KEY (personId), "
            + "UNIQUE (email_userName)"
            + ")";

  String createFriendsTable =
          "CREATE TABLE Friends("
        + "personId     INT NOT NULL, "
        + "friendId     INT NOT NULL, "
        + "status       VARCHAR2(50) NOT NULL, "
        + "PRIMARY KEY (personId, friendId), "
        + "FOREIGN KEY (personId) REFERENCES Persons(personId), "
        + "FOREIGN KEY (friendId) REFERENCES Persons(personId), "           
        + ")";

Answer 1

  String createFriendsTable =
          "CREATE TABLE Friends("
        + "personId     INT NOT NULL, "
        + "friendId     INT NOT NULL, "
        + "status       VARCHAR2(50) NOT NULL, "
        + "PRIMARY KEY (personId, friendId), "
        + "FOREIGN KEY (personId) REFERENCES Persons(personId), "
        + "FOREIGN KEY (friendId) REFERENCES Persons(personId), "           
                                                              ^
        + ")";

额外尾随逗号