MySQL学习小记(一)

大致练习一些常用的命令了,日后直接查,实在不想记这玩意hhh

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dos窗口下mysql清屏

system cls;

添加新用户及密码

CREATE USER 'knight'@'localhost' IDENTIFIED BY '123456';

查看所有用户

SELECT user, host FROM mysql.user;

给本地的用户赋予特权

GRANT ALL PRIVILEGES ON * . * TO 'knight'@'localhost';

查看用户的特权

SHOW GRANTS FOR 'knight'@'localhost';

刷新MySQL的系统权限相关表,否则会出现拒绝访问

FLUSH PRIVILEGES;

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新增数据库并新增员工表

CREATE DATABASE acme;

SHOW DATABASES;

USE acme;

CREATE TABLE users(
id INT AUTO_INCREMENT, #自动增加
first_name VARCHAR(100),
last_name VARCHAR(100),
email VARCHAR(75),
password VARCHAR(255), #加密后会很长
location VARCHAR(100),
dept VARCHAR(75), #部门
is_admin TINYINT(1), #布尔值
register_date DATETIME,
PRIMARY KEY(id) #主键值
);

工作台

MySQL :: Download MySQL Workbenchhttps://dev.mysql.com/downloads/workbench/

在刚才建的表中新增记录 

SELECT * FROM users;
INSERT INTO users(first_name, last_name, email, password, location, dept, is_admin, register_date)
values ('Jack', 'Tong', 'jack@email.com', '666666', 'Beijing', 'development', 1, now());

# 新增多个记录
INSERT INTO users(first_name, last_name, email, password, location, dept, is_admin, register_date)
values ('Marry', 'Yu', 'mary@email.com', 'ghshtrh', 'Beijing', 'manager', 1, now()),
('Lora', 'Aba', 'lora@email.com', '547337', 'Tianjin', 'lawyer', 0, now());

查看字段

SELECT first_name, last_name, register_date FROM users;

 

查看指定的字段有哪些记录

SELECT * FROM users WHERE location='Beijing' AND dept='development';

 

SELECT * FROM users WHERE is_admin = 0;

 

 删除记录

DROP FROM users WHERE id = 2;

 (新增了几个记录,以免不够用来测试)

 修改信息

UPDATE users SET email='lisi@gmail.com' WHERE id=5; 

新增字段

ALTER TABLE users ADD age VARCHAR(3);

修改字段的数据类型 

ALTER TABLE users MODIFY COLUMN age INT(3)

按照字段进行升序/降序

SELECT * FROM users ORDER BY last_name ASC;

  

SELECT * FROM users ORDER BY age DESC;

联系不同的字段

SELECT CONCAT(first_name, '-', last_name) AS 'Name', dept FROM users;

查看字段有哪些种类

SELECT location FROM users;

SELECT DISTINCT location FROM users;

 

 查看指定范围有哪些人

SELECT first_name,age FROM users WHERE age BETWEEN 26 AND 30;

  

SELECT * FROM users WHERE dept IN('designer', 'staff');

匹配所有职位以***开头或者结尾的员工(NOT LIKE 是求不含***的)

SELECT * FROM users WHERE dept LIKE 'd%';

SELECT * FROM users WHERE dept LIKE '%op%';

SELECT * FROM users WHERE dept LIKE '%ff';

常用命令

MySQL cheatsheet (devhints.io)https://devhints.io/mysql