MySQL - add index to existing table using CREATE INDEX

In this article, we would like to show you how to add index to an existing table using CREATE INDEX statement in MySQL.

Quick solution:

CREATE INDEX `index_name`
ON `table_name` (`column1`, `column2`, `columnN`);

Practical example

To show how the CREATE INDEX statement works, we will use the following table:

Note:

At the end of this article you can find database preparation SQL queries.

Example 1 - one column index

In this example, we will create an index for the salary column in users table.

Query:

CREATE INDEX `salary_index`
ON `users` (`salary`);

Result:

1. Using query

SHOW INDEX FROM `users` FROM `dirask`;    -- where users-table_name, dirask-database_name

2. Using HeidiSQL

Example 2 - two column index

In this example, we will create an index on the name and surname columns in users table.

Query:

CREATE INDEX `full_name_index`
ON `users` (`name`, `surname`);

Result:

1. Using query

SHOW INDEX FROM `users` FROM `dirask`;    -- where users-table_name, dirask-database_name

2. Using HeidiSQL

Database preparation

create_tables.sql file:

CREATE TABLE `users` (
	`id` INT(10) UNSIGNED NOT NULL AUTO_INCREMENT,
	`name` VARCHAR(50) NOT NULL,
	`surname` VARCHAR(50) NOT NULL,
    `salary` DECIMAL(15,2) NOT NULL,
	PRIMARY KEY (`id`)
);

insert_data.sql file:

INSERT INTO `users`
	( `name`, `surname`, `salary`)
VALUES
	('John', 'Stewart', '3512.00'),
	('Chris', 'Brown', '1344.00'),
	('Kate', 'Lewis', '6574.00'),
	('Ailisa', 'Gomez', '6500.00'),
	('Gwendolyn', 'James', '4200.00'),
	('Simon', 'Collins', '3320.00'),
	('Taylor', 'Martin', '1500.00'),
	('Andrew', 'Thompson', '2100.00');