MySQL日常练习——单表DDL DML DQL

1.建表语句——DDL

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) 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;

2.插入语句——DML

insert into student values(0,'2024-02-25 10:00:00','刘德华','123456','12345678901',62,'男','男神');
insert into student values(0,'2024-02-25 10:00:00','刘青云','123456','12345678901',65,'男','演员');
insert into student values(0,'2024-02-25 10:00:00','周星驰','123456','12345678901',61,'男','爱情');
insert into student values(0,'2024-02-25 10:00:00','张翰','123456','12345678901',32,'男','流星雨');
insert into student values(0,'2024-02-25 10:00:00','王祖贤','123456','12345678901',27,'女','女神');
insert into student  (userName,age,introduce)values('刘亦菲',37,'神仙姐姐');
select * from student;

3.基础查询语句——DQL

#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,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;