MySQL

安装 MySQL（过程参考【精选】2023 年 MySQL 8.0 安装配置 最简易（保姆级）_mysql8.0安装配置教程_mobeicanyue的博客-CSDN博客）

win + R 管理员权限使用cmd，验证MySQL安装是否成功

mysql -u root -p

安装 MySQL Workbench （过程参考MySQL及MySQL Workbench下载与安装 - 知乎 (zhihu.com)）

创建表 create table（来源牛客SQL109）

DROP TABLE IF EXISTS `Customers`;
CREATE TABLE IF NOT EXISTS `Customers`(
    cust_name VARCHAR(255) NOT NULL COMMENT '顾客id',
    cust_contact VARCHAR(255) NOT NULL COMMENT '顾客联系方式',
    cust_state VARCHAR(255) NOT NULL COMMENT '顾客州',
    cust_email VARCHAR(255) NOT NULL COMMENT '顾客email'
  );
INSERT `Customers` VALUES ('cust10','8695192','MI','cust10@cust.com'),('cust1','8695193','MI','cust1@cust.com'),('cust2','8695194','IL','cust2@cust.com');

查询 select

select * from Customers

添加 insert / insert into

insert `Customers`
values ('cust20','8695195','NEW','cust20@cust.com')

更新 update

涉及到where语句中条件不为主键，MySQL Workbench默认安全更新模式，关闭安全更新模式即可（mysql workbench 关闭安全更新模式_mysqlworkbench关闭安全模式-CSDN博客）

update Customers
set cust_state = 'UPDATED'
where cust_name = 'cust20'

删除 delete

delete from Customers
where cust_name = 'cust20'

排序 order by，asc升序（不写则默认升序），desc降序

select * from Customers
order by cust_contact asc

select * from Customers
order by cust_contact desc

联合 unoin 两张表，order by需要在末尾，而不能是两个子表各自都有

select cust_name, cust_contact, cust_email 
from Customers 
where cust_state = 'MI'
union 
select cust_name, cust_contact, cust_email 
from Customers 
where cust_state = 'IL'
order by cust_name