编辑代码

CREATE DATABASE test;
use test;
CREATE TABLE student (
	id int AUTO_INCREMENT PRIMARY KEY,
	name varchar(255),
	address varchar(255) NOT NULL,
	city varchar(255) NULL
);

INSERT INTO test.student VALUES (1, '刘一', '郑十家隔壁', '河南');
INSERT INTO student VALUES (2, '陈二',  '李四家隔壁', '安徽');
INSERT INTO student VALUES (3, '张三',  '白娘子家隔壁', '杭州');
INSERT INTO student VALUES (4, '李四',  '许仙家隔壁', '杭州');
INSERT INTO student VALUES (5, '王五',  '李四家隔壁', '杭州');
INSERT INTO student VALUES (6, '赵六',  '赵六家隔壁', '杭州');
INSERT INTO student VALUES (7, '孙七',  '张三家隔壁', '杭州');
INSERT INTO student VALUES (8, '周八',  '雷峰塔附近', '杭州');
INSERT INTO student VALUES (9, '吴九',  '孙七家隔壁', '杭州');
INSERT INTO student VALUES (10, '郑十',  '周八家隔壁', '杭州');

ALTER TABLE test.student
ADD age INT NULL;

UPDATE test.student
set age = 14
WHERE id = 3;
 
SELECT * FROM test.student
-- WHERE id >= 4 AND city = '杭州' 
WHERE city IN ('杭州','安徽')
-- WHERE id BETWEEN 4 AND 8
-- WHERE name LIKE '李%';
--'%'匹配任意个任意字符  '_'匹配一个任意字符
ORDER BY id ASC;
-- ORDER BY id DSC;

SELECT DISTINCT city FROM test.student;

CREATE DATABASE egg;

use egg;

CREATE TABLE egg_record (
    id int AUTO_INCREMENT PRIMARY KEY,
	name varchar(255),
	address varchar(255) NOT NULL,
	city2 varchar(255) NULL
);

DROP DATABASE egg;