MySql单表操作学习DDL_DML_DQL语句

  数据库名称可以为【schoolDB】,字符集【utf8】,排序规则【utf8_general_ci】。

1、 创建数据表——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) 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;

2、插入语句——DML

INSERT INTO student VALUES(0,'2022-02-02 10:10:10','葫芦爷爷','123123','12312312311',
69,'男','福禄哇的爷爷，孙子快救我。');
INSERT INTO student VALUES(0,'2022-02-02 10:10:10','蛇精','123123','12312312311',
28,'女','我看这蛇精也是风韵犹存');
INSERT INTO student VALUES(0,'2022-02-02 10:10:10','穿山甲','123123','12312312311',
9,'男','保护动物不让吃。');
INSERT INTO student VALUES(0,'2022-02-02 10:10:10','蝴蝶妹妹','123123','12312312311',
17,'女','挺好看的一小姑娘');
INSERT INTO student (userName,age,introduce) VALUES ('山神',255,'孕育了福禄娃种子');

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,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;