阿摩線上測驗
30 有兩個資料表，license 儲存所有證照的基本資料，student 則是儲存所有學生們已經考上的證照資料，license
的主鍵為 license_id，也是 student 的外來鍵，建立資料表的 SQL 指令如下：
CREATE TABLE license (license_id INT PRIMARY KEY, license_category VARCHAR(20) NOT NULL, licensing_units VARCHAR(50) NOT NULL, license_name VARCHAR(100) NOT NULL, series VARCHAR(50) NOT NULL, count INT NOT NULL ); CREATE TABLE student (student_id VARCHAR(10) DEFAULT NULL, name VARCHAR(10) NOT NULL, year INT NOT NULL, semester INT NOT NULL, date DATE NOT NULL, license_id INT, CONSTRAINT ______________________ )
請問在填空位置內，正確的設定外來鍵的語法為何？
(A)FK1 FOREIGN KEY (license_id) REFERENCES license (license_id)
(B)FOREIGN KEY (license_id) REFERENCES license_id
(C)FK1 FOREIGN KEY (license_id) REFERENCES license_id
(D)FOREIGN KEY (student) REFERENCES license (license_id)
CREATE TABLE license (license_id INT PRIMARY KEY, license_category VARCHAR(20) NOT NULL,
licensing_units VARCHAR(50) NOT NULL, license_name VARCHAR(100) NOT NULL, series VARCHAR(50)
NOT NULL, count INT NOT NULL );
CREATE TABLE student (student_id VARCHAR(10) DEFAULT NULL,
name VARCHAR(10) NOT NULL, year INT NOT NULL, semester INT NOT NULL,
date DATE NOT NULL, license_id INT,
CONSTRAINT ______________________ )
(A)FK1 FOREIGN KEY (license_id) REFERENCES license (license_id)
(B)FOREIGN KEY (license_id) REFERENCES license_id
(C)FK1 FOREIGN KEY (license_id) REFERENCES license_id
(D)FOREIGN KEY (student) REFERENCES license (license_id)
答案：登入後查看
統計： A(63), B(32), C(24), D(33), E(0) #659881
統計： A(63), B(32), C(24), D(33), E(0) #659881
