1. CREATE TABLE `app_user` (
    2. `id` bigint(20) unsigned NOT NULL AUTO_INCREMENT,
    3. `name` varchar(50) DEFAULT '' COMMENT '用户昵称',
    4. `email` varchar(50) NOT NULL COMMENT '用户邮箱',
    5. `phone` varchar(20) DEFAULT '' COMMENT '手机号',
    6. `gender` tinyint(4) unsigned DEFAULT '0' COMMENT '性别（0:男；1：女）',
    7. `password` varchar(100) NOT NULL COMMENT '密码',
    8. `age` tinyint(4) DEFAULT '0' COMMENT '年龄',
    9. `create_time` datetime DEFAULT CURRENT_TIMESTAMP,
    10. `update_time` timestamp NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
    11. PRIMARY KEY (`id`)
    12. ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COMMENT='app用户表'
    14. SHOW INDEX FROM app_user
    15. ALTER TABLE `app_user` ADD FULLTEXT INDEX `name`(`name`)
    16. CREATE INDEX app_user_name ON app_user (`name`) ;
    17. EXPLAIN SELECT * FROM app_user WHERE `name` = '用户9999'
    18. DROP INDEX app_user_name ON app_user;

    索引在小数据量的时候，用处不大，但在大数据的时候，区别十分明显