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单选题
Which statement explicitly names a constraint?()
A

ALTER TABLE student_grades ADD FOREIGN KEY (student_id) REFERENCES students (student_id);

B

ALTER TABLE student_grades ADD CONSTRAINT NAME = student_id_fk FOREIGN KEY (student_id) REFERENCES students (student_id);

C

ALTER TABLE student_grades ADD CONSTRAINT student_id_fk FOREIGN KEY (student_id) REFERENCES students (student_id);

D

ALTER TABLE student grades ADD NAMED CONSTRAINT student_id_fk FOREIGN KEY (student_id) REFERENCES students (student_id);

E

ALTER TABLE student grades ADD NAME student_id_fk FOREIGN KEY (student_id) REFERENCES students (student_id);


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考题 单选题Which statement explicitly names a constraint?()A ALTER TABLE student_grades ADD FOREIGN KEY (student_id) REFERENCES students(student_id);B ALTER TABLE student_grades ADD CONSTRAINT NAME = student_id_fk FOREIGN KEY (student_id) REFERENCES students(student_id);C ALTER TABLE student_grades ADD CONSTRAINT student_id_fk FOREIGN KEY (student_id) REFERENCES students(student_id);D ALTER TABLE student grades ADD NAMED CONSTRAINT student_id_fk FOREIGN KEY (student_id) REFERENCES students(student_id);E ALTER TABLE student grades ADD NAME student_id_fk FOREIGN KEY (student_id) REFERENCES students(student_id);

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考题 单选题You need to modify the STUDENTS table to add a primary key on the STUDENT_ID column. The table is currently empty. Which statement accomplishes this task?()A ALTER TABLE students ADD PRIMARY KEY _ id;B ALTER TABLE students ADD CONSTRAINT PRIMARY KEY (student_id);C ALTER TABLE students ADD CONSTRAINT stud_id_pk PRIMARY KEY student_id;D ALTER TABLE students ADD CONSTRAINT stud_id_pk PRIMARY KEY (student_id);E ALTER TABLE students MODIFY CONSTRAINT stud_id_pk PRIMARY KEY (student_id);

考题 单选题Which SQL statement defines a FOREIGN KEY constraint on the DEPTNO column of the EMP table?()A CREATE TABLE EMP (empno NUMBER(4), ename VARCHAR2(35), deptno NUMBER(7,2) NOT NULL, CONSTRAINT emp_deptno_fk FOREIGN KEY deptno REFERENCES dept deptno);B CREATE TABLE EMP (empno NUMBER(4), ename VARCHAR2(35), deptno NUMBER(7,2) CONSTRAINT emp_deptno_fk REFERENCES dept (deptno));C CREATE TABLE EMP (empno NUMBER(4), ename VARCHAR2(35), deptno NUMBER(7,2) NOT NULL, CONSTRAINT emp_deptno_fk REFERENCES dept (deptno) FOREIGN KEY (deptno));D CREATE TABLE EMP (empno NUMBER(4), ename VARCHAR2(35), deptno NUMBER(7,2) FOREIGN KEY CONSTRAINT emp_deptno_fk REFERENCES dept (deptno));

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