MySQL日常语句练习——单表DDL_DML_DQL语句练习

CREATE TABLE `student` (
  `id` int(11) NOT NULL AUTO_INCREMENT COMMENT '学号',
  `createDate` datetime DEFAULT NULL COMMENT '创建时间',
  `userName` varchar(20) DEFAULT NULL COMMENT '用户名',
  `pwd` varchar(36) DEFAULT NULL COMMENT '密码',
  `phone` varchar(11) DEFAULT NULL COMMENT '手机号',
  `age` tinyint(3) unsigned DEFAULT NULL COMMENT '年龄',
  `sex` char(2) DEFAULT '男' COMMENT '性别',
  `introduce` varchar(255) DEFAULT NULL COMMENT '简介',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8;

insert into student values(0,'2024-02-25 10:00:00','刘德华','123654',
'15612345678',62,'男','永远的男神，爱你一万年，爱你经得起考研。');
insert into student values(0,'2024-02-25 10:00:00','刘青云','123154',
'15612345678',65,'男','真正的演员，好角色用心演绎。');
insert into student values(0,'2024-02-25 10:00:00','周星驰','123624',
'15612345678',61,'男','所有的电影都没有对爱情有过轻视。');
insert into student values(0,'2024-02-25 10:00:00','张翰','122654',
'15612345678',32,'男','一起坐死在流星雨下。');
insert into student values(0,'2024-02-25 10:00:00','王祖贤','223654',
'15612345678',27,'女','你再美你能比过王祖贤吗？');
insert into student (userName,age,introduce)values('刘亦菲',37,'神仙姐姐');

# 1、基础查询
select * from student;
# 2、分列匿名以及筛选数据查询
select userName as '姓名',age 年龄,sex '性别',introduce '简介'
from student 
where pwd is not null;
# 3、去重查询
select distinct sex '性别类型' from student;
# 4、排序查询
select userName as '姓名',age 年龄,sex '性别',introduce '简介' from student ORDER BY age desc;
# 5、分页查询·limit这是个重载函数，
# 1个参数的limit用法是显示多少条信息
select * from student LIMIT 2;
# 2个参数，参数1：从第N条开始查询，N的起始坐标为0条。参数2：查询条数
select * from student limit 4,2;