mysql sql添加主键

ALTER TABLE table_name ADD PRIMARY KEY (column_name);

ALTER TABLE table_name ADD PRIMARY KEY (column1, column2, ...);

CREATE TABLE students (
    id INT,
    name VARCHAR(50),
    age INT
);

ALTER TABLE students ADD PRIMARY KEY (id);

ALTER TABLE students ADD PRIMARY KEY (id, name);

INSERT INTO students (id, name, age) VALUES (1, 'Alice', 20) ON DUPLICATE KEY UPDATE age = 20;

ALTER TABLE students MODIFY id INT NOT NULL;

ALTER TABLE students PARTITION BY RANGE (id) (
    PARTITION p0 VALUES LESS THAN (100),
    PARTITION p1 VALUES LESS THAN (200),
    PARTITION p2 VALUES LESS THAN MAXVALUE
);