SQL PRIMARY KEY

Using the primary key in SQL

	/*CREATe TABLE students (
  	id int(20) NOT NULL,
  	name VARCHAR(200),
  
  	PRIMARY KEY (id)
 	 );*/
	/*INSERT INTO students(id,name) 
	VALUES
	(1,'David'),
	(2,'James'),
	(3,'John');
	*/

	-- SELECT * From students;
	-- Alter TAble students MODIFY id INt AUTO_INCREMENT ;
	-- ALTER TABLE students MODIFY COLUMN id AUTO_INCREMENT=1;
	-- ALTER TABLE students MODIFY COLUMN id INT AUTO_INCREMENT;
	-- SELECT * FROM students;
	/*INSERT INTO students(name) 
	VALUES('Abudi');8
    */
    /*INSERT INTO students(name) 
	VALUES
	('Esther'),
  	('Jovia'),
	('Doryn');
	*/
  	-- SELECT * FROM students;
    /*CREATE TABLE results (
  	id int(20) AUTO_INCREMENT,
  	subject VARCHAR(100) NOT NULL,
  	marks INT(3),
 	PRIMARY KEY(id)
	);
	*/
	-- SELECT * FROM results;
    /*CREATE TABLE staff (
      id INT(20) AUTO_INCREMENT,
      name VARCHAR(200) NOT NULL,
      PRIMARY KEY(id)
     );
     */
     /*CREATE TABLE payments (
      id int NOT NULL AUTO_INCREMENT,
      PRIMARY KEY(id),
      student_id INT NOT NULL,
      amount INT(8)
     );*/
     /*CREATE TABLE results (
       id int NOT NULL AUTO_INCREMENT,
       subject VARCHAR(100) NOT NULL,
       marks INT(3),
     );
     */