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)
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