如何使用主鍵、外鍵、唯一而不是 null 創建 3 個表並檢查約束

Question

我想為他們創建 3 個表和 3 個外鍵，但我收到了這個錯誤

ORA-00942: 表或視圖不存在

我的主要項目問題在底部。 如何不出現此錯誤。 感謝幫助。

1.請創建關於一個主題的相關三個表（用於exp.Student、Employees、Products、Books、Club_Membership、Hobbies等），每個表必須至少包含一個主鍵、一個外鍵、唯一的，而不是null並檢查約束.

CREATE TABLE Student
(
    StudentID varchar2(10) NOT NULL,
    StudentName varchar2(50)NOT NULL, 
    StudentAddress varchar2(50),
    typeID varchar2(10)
    constraint pk_Student PRIMARY KEY (StudentID),
    constraint fk_types foreign key (typeID) references Types (typeID)
);

CREATE TABLE Book
(
    BookID varchar2(10) NOT NULL,
    BookName varchar2(40) NOT NULL UNIQUE, 
    ISBN number UNIQUE,
    loan_date NOT NULL,
    constraint pk_Book PRIMARY KEY (BookID),
    constraint fk_History FOREIGN KEY (loan_date) REFERENCES History (loan_date)
);         

CREATE TABLE History
(
    loan_date NUMBER NOT NULL,
    BookID varchar2(10),
    return_date NUMBER,
    constraint pk_History PRIMARY KEY (loan_date),
    constraint fk_Book    FOREIGN KEY (BookID) REFERENCES Book(BookID)
    
);

Answer 1

首先創建表，然后創建主鍵，然后創建外鍵。

CREATE TABLE ABC ...
CREATE TABLE XYZ ...

ALTER TABLE ABC ADD CONSTRAINT PK_ABC PRIMARY KEY ...
ALTER TABLE XYZ ADD CONSTRAINT PK_XYZ PRIMARY KEY ...

ALTER TABLE ABC ADD CONSTRAINT FK_ABC FOREIGN KEY ...    
ALTER TABLE XYZ ADD CONSTRAINT FK_XYZ FOREIGN KEY ...