Mysql 查询以某个字符开头的语句和LIKE的使用

SELECT * FROM `tb_user` where userName like '小%';
 
SELECT * FROM `tb_user` where userName like '%小%';
 
SELECT * FROM `tb_user` where userName like '%小';
 
SELECT * FROM `tb_user` WHERE userName LIKE '小';
 
SELECT * FROM `tb_user` where left(userName,1)='s';
 
SELECT * FROM `tb_user` where substring(userName,1,1)='s';

 
CREATE DATABASE /*!32312 IF NOT EXISTS*/`testdb` /*!40100 DEFAULT CHARACTER SET utf8 */;
 
USE `testdb`;
 
DROP TABLE IF EXISTS `tb_user`;
 
CREATE TABLE `tb_user` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `userName` varchar(18) DEFAULT NULL,
  `birth` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=8 DEFAULT CHARSET=utf8;
 
 
 
insert  into `tb_user`(`id`,`userName`,`birth`) values 
 
(1,'小军','1993-06-05 00:00:00'),
 
(2,'小明','1993-04-03 00:00:00'),
 
(3,'呵呵','2020-12-13 17:43:16'),
 
(4,'tt','2020-12-13 17:43:23'),
 
(5,'ta','2020-12-31 17:45:44'),
 
(6,'st','2020-12-13 17:45:53'),
 
(7,'均小','2020-12-13 17:47:18');