PRIMARY KEY

Primary Key (Inline)

CREATE TABLE IF NOT EXISTS `course`(
	`course_id` CHAR(12) NOT NULL PRIMARY KEY,
	`course_code` VARCHAR(40) NOT NULL,
	`course_title` VARCHAR(40) NOT NULL,
	`course_dept` VARCHAR(4) NOT NULL,
	`course_credit` FLOAT(3,1),
	CHECK (`course_credit` IN (3.0, 1.5))
);
SHOW INDEX FROM `course`;

Primary Key

CREATE TABLE IF NOT EXISTS `course`(
	`course_id` CHAR(12) NOT NULL,
	`course_code` VARCHAR(40) NOT NULL,
	`course_title` VARCHAR(40) NOT NULL,
	`course_dept` VARCHAR(4) NOT NULL,
	`course_credit` FLOAT(3,1),
	CHECK (`course_credit` IN (3.0, 1.5)),
	PRIMARY KEY (`course_id`)
);

SHOW INDEX FROM `course`;

Composite Primary Key

CREATE TABLE IF NOT EXISTS `course`(
	`course_id` CHAR(12) NOT NULL,
	`course_code` VARCHAR(40) NOT NULL,
	`course_title` VARCHAR(40) NOT NULL,
	`course_dept` VARCHAR(4) NOT NULL,
	`course_credit` FLOAT(3,1),
	CHECK (`course_credit` IN (3.0, 1.5)),
	PRIMARY KEY (`course_id`, `course_code`)
);

SHOW INDEX FROM `course`;

Alter Table

CREATE TABLE IF NOT EXISTS `course`(
	`course_id` CHAR(12) NOT NULL,
	`course_code` VARCHAR(40) NOT NULL,
	`course_title` VARCHAR(40) NOT NULL,
	`course_dept` VARCHAR(4) NOT NULL,
	`course_credit` FLOAT(3,1),
	CHECK (`course_credit` IN (3.0, 1.5))
);

ALTER TABLE `course` ADD CONSTRAINT `PK_course` PRIMARY KEY (`course_id`);

SHOW INDEX FROM `course`;

Drop Primary Key

CREATE TABLE IF NOT EXISTS `course`(
	`course_id` CHAR(12) NOT NULL,
	`course_code` VARCHAR(40) NOT NULL,
	`course_title` VARCHAR(40) NOT NULL,
	`course_dept` VARCHAR(4) NOT NULL,
	`course_credit` FLOAT(3,1),
	CHECK (`course_credit` IN (3.0, 1.5))
);

ALTER TABLE `course` ADD CONSTRAINT `PK_course` PRIMARY KEY (`course_id`);

SHOW INDEX FROM `course`;

ALTER TABLE `course` DROP PRIMARY KEY;

SHOW INDEX FROM `course`;