About mysql database (install and uninstall)

Composition Database

Library: storing a plurality of tables - Folder
Table: contains a plurality of records of the same structure - file
records: the key comprises a plurality of key-value pairs of data - binary data
fields: description information - == key-value information itself - binary data

What is fields and records?

Red box is shown in the following fields

A data table is divided into rows and columns, a row is hop record. There may be many fields, it is the individual properties. Student such a table, there are studentname, id field and the like, it is one of the stations. Together they make up hop record.

Classification database

Relations with non-relational

关系:数据库中表与表之间有关系,联系,  -mysql
非关系:没有表概念  -radis,mongodb(介于关系与非关系)

Memory and hard drive

硬盘:数据可以永久存储 -mysql ,mongodb 
内存:数据的存取效率非常高  -redis,memcache

sql and nosql

sql: database operated by sql statement
nosql: (value is a record) in the form of database operations is the key-value

Uninstall

"""
前提）启动终端，输入 mysql，如果不是提示 不是内部或外部命令，代表已安装数据库

1）直接连入
    i 搜索：服务，检索mysql服务，有
        停止服务，并移除服务 - 启动管理员终端：mysqld --remove
            
    ii 搜索：服务，检索mysql服务，无 （mysql使用命令启动）
        停止服务，启动管理员终端
            tasklist | findstr mysql
            taskkill /pid 进程pid /f
    
2）连接超时
    搜索：服务，检索mysql服务，移除服务即可
    
3）移除环境变量

总结：如果能连入，先停止服务 | 如果添加了服务，就移除服务 | 取消环境变量配置
"""

installation

"""
1、解压免安装版本（5.6 - 没有初始密码）
2、配置环境变量：数据库绝对路径下的bin
3、配置服务：
    启动管理员终端：mysqld --install [nmysql]
"""