MySQL 8 Cookbook

Add index

You can add an index by executing the ALTER TABLE ADD INDEX command. For example, if you want to add an index on last_name, see the following code:

mysql> ALTER TABLE employees ADD INDEX (last_name);Query OK, 0 rows affected (1.28 sec)Records: 0  Duplicates: 0  Warnings: 0mysql> SHOW CREATE TABLE employees\G*************************** 1. row ***************************       Table: employeesCreate Table: CREATE TABLE `employees` (  `emp_no` int(11) NOT NULL,  `birth_date` date NOT NULL,  `first_name` varchar(14) NOT NULL,  `last_name` varchar(16) NOT NULL,  `gender` enum('M','F') NOT NULL,  `hire_date` date NOT NULL,  PRIMARY KEY (`emp_no`),  KEY `name` (`first_name`,`last_name`),  KEY `last_name` (`last_name`)) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 ...