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?（）AALTER TABLE students ADD PRIMARY KEY student_id;BALTER TABLE students ADD CONSTRAINT PRIMARY KEY (student_id);CALTER TABLE students ADD CONSTRAINT stud_id_pk PRIMARY KEY student_id;DALTER TABLE students ADD CONSTRAINT stud_id_pk PRIMARY KEY (student_id);EALTER TABLE students MODIFY CONSTRAINT stud_id_pk PRIMARY KEY (student_id);
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 student_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);
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