我想在现有主键中添加更多主键

Question

我想通过组合 3 列来设置主键，但我错误地用一列设置了键。我应该如何将其他两列添加到现有的主键中。

CREATE TABLE facultyQualification(
    facultyID CHAR(5) NOT NULL,
    level_ VARCHAR(15) NOT NULL,
    Exam_Degree VARCHAR(30) NOT NULL,
    School_College VARCHAR(50) NOT NULL,
    Board_Uni VARCHAR(30) NOT NULL,
    year_of_passing DATE NOT NULL,
    Max_marks_grades INT NOT NULL,
    marks_grade_obtained INT NOT NULL,
    perscent_marks INT NOT NULL,
    division VARCHAR(10) NOT NULL,
    achievement VARCHAR(50),
    FOREIGN KEY(facultyID) REFERENCES facultyPersonal(facultyID)
);
SELECT * FROM facultyQualification;
ALTER TABLE facultyQualification
ADD PRIMARY KEY (facultyID);

我想做的主键是（facultyID，level_，year_of_passing）。

Answer 1

你可以做：

alter table facultyQualification drop primary key;

alter table facultyQualification 
add primary key (facultyID, level_, year_of_passing);

请参阅DB Fiddle 的示例。