编辑代码

CREATE DATABASE test;
use test;
CREATE TABLE student (
	id int AUTO_INCREMENT,
	name varchar(255),
	address varchar(255),
	city varchar(255),
    salary int,
    PRIMARY KEY (id)
);

INSERT INTO student VALUES (1, '刘一', '郑十家隔壁', '河南', 313);
INSERT INTO student VALUES (2, '陈二',  '李四家隔壁', '安徽', 2023);
INSERT INTO student VALUES (3, '张三',  '白娘子家隔壁', '杭州', 11);

ALTER TABLE student ADD COLUMN age int(10) DEFAULT 18;

select * from student;


-- CREATE TABLE person LIKE student;
-- INSERT INTO person select * from student;
-- select * from person;

-- CREATE TABLE children select * from student WHERE id = 2;
-- select * from children;


CREATE TABLE children (
    id int AUTO_INCREMENT,
    remark varchar(2048) DEFAULT '备注',
    PRIMARY KEY (id)
);

-- INSERT INTO children VALUES (1, '你好啊');
-- INSERT INTO children VALUES (2, '不承担VB就是VB');

-- select * from children;

-- 联结查询：连接数据的桥梁
-- select a.name,b.remark from student a JOIN children b on a.id = b.id;

-- 子查询：嵌套查询的力量
-- select * from student where salary > (select AVG(salary) from student);

-- 视图：简化复杂查询
-- CREATE VIEW high_earners AS
-- select name, salary from student where salary > 1000;