MySQL

1学生表DDL

CREATE TABLE `student` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `createdate` datetime DEFAULT NULL,
  `username` varchar(20) DEFAULT NULL,
  `pwd` varchar(36) DEFAULT NULL,
  `phone` varchar(11) DEFAULT NULL,
  `age` tinyint(3) DEFAULT NULL,
  `sex` char(2) DEFAULT NULL,
  `introduce` varchar(255) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8;

2插入学生信息DML

INSERT into student values(0,'2024-02-25 10:00:00','赵玲','123','15683440435',16,'女','逍遥');
INSERT into student values(0,'2024-02-25 10:00:00','王语嫣','123','15683440435',17,'女','木芙蓉');
INSERT into student values(0,'2024-02-25 10:00:00','龙姑娘','123','15683440435',22,'女','好好过日子');
INSERT into student values(0,'2024-02-25 10:00:00','杨过','123','15683440435',18,'男','一场杨过误终身');
INSERT into student values(0,'2024-02-25 10:00:00','杨瑶','123','15683440435',27,'男','大儿子');
INSERT into student(username,age,introduce) values('黄衣女子',26,'大女儿');

 效果展示

3基础查询测试DQL

SELECT * FROM student;
select username '姓名',age '年龄',sex '性别',introduce '介绍'
from student
where pwd is not null;
#从第四条（3+1）开始查询，查两条
select * from student limit 3,2;
#order by根据数据类型进行排序会更加准确
select * from student ORDER BY age desc limit 3;
select DISTINCT sex '性别类型' from student;