更新笔记属性

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date: 2025-01-19
tags:
- Notes
- MySql
lastUpdated: 2025-01-20T10:10:00
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## sql、DB、DBMS分别是什么,他们之间的关系?
DB:
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date: 2025-01-19
tags:
- Notes
- MySql
lastUpdated: 2025-01-20T10:10:00
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## 卸载MySQL
1. 双击安装包,点击下一步,然后点击remove。卸载。
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date: 2025-01-19
tags:
- Notes
- MySql
lastUpdated: 2025-01-20T10:10:00
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## 常用命令
退出MySQL:exit;
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date: 2025-01-19
tags:
- Notes
- MySql
lastUpdated: 2025-01-20T10:10:00
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## 简单查询(DQL)
语法格式:select 字段名1 ,字段名2 ,字段名3,。。。From 表名;
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date: 2025-01-19
tags:
- Notes
- MySql
lastUpdated: 2025-01-20T10:10:00
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## 条件查询
语法:
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date: 2025-01-19
tags:
- Notes
- MySql
lastUpdated: 2025-01-20T10:10:00
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## 排序
语法:
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date: 2025-01-19
tags:
- Notes
- MySql
lastUpdated: 2025-01-20T10:10:00
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## 分组函数(多行处理函数)
多行处理函数特点:输入多行,输出结果是一行
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date: 2025-01-19
tags:
- Notes
- MySql
lastUpdated: 2025-01-20T10:10:00
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## 连接查询分类
根据语法出现年代划分:
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date: 2025-01-19
tags:
- Notes
- MySql
lastUpdated: 2025-01-20T10:10:00
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## 表的创建
建表语句:
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date: 2025-01-19
tags:
- Notes
- MySql
lastUpdated: 2025-01-20T10:10:00
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## 删表
```sql
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date: 2025-01-19
tags:
- Notes
- MySql
lastUpdated: 2025-01-20T10:10:00
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语法:
```sql
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date: 2025-01-19
tags:
- Notes
- MySql
lastUpdated: 2025-01-20T10:10:00
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## 约束和常见约束
在创建表时可以添加约束,可以给表的字段增加约束,添加约束的目的是为了表中数据的完整性、合法性、唯一性
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date: 2025-01-19
tags:
- Notes
- MySql
lastUpdated: 2025-01-20T10:10:00
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## 存储引擎和字符集
MySQL 默认存储引擎是 InnoDB 方式。
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date: 2025-01-19
tags:
- Notes
- MySql
lastUpdated: 2025-01-20T10:10:00
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## 事务概述
一个事务时一个完整的逻辑单元,不可再分。
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date: 2025-01-19
tags:
- Notes
- MySql
lastUpdated: 2025-01-20T10:10:00
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## 索引作用
相当于一本书的目录。
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date: 2025-01-19
tags:
- Notes
- MySql
lastUpdated: 2025-01-20T10:10:00
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## 什么是视图
视图是一种根据查询(也就是SELECT表达式)定义的数据库对象,用于获取想要看到和使用的局部数据。
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date: 2025-01-19
tags:
- Notes
- MySql
lastUpdated: 2025-01-20T10:10:00
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## 什么是三范式
设计表的依据,按照这个三范式设计的表不会出现数据冗余。
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date: 2025-01-19
tags:
- Notes
- MySql
lastUpdated: 2025-01-20T10:10:00
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## 练习
基础: