Introduction and installation of MySQL

1. Introduction of database (1) related concepts of database:

   data: symbols that describe things, often expressed with text, pictures, audio, and video.

   database: a warehouse in which data is stored in a certain format.

   database management system: how to organize and store data scientifically, and how to obtain and maintain data efficiently

   database type: Oracle, mysql, SQL server, DB2, foxpro, Access

   database application: an application that stores data in a database and interacts directly with the user.

(2) introduction of relational database:

   uses structured query statements (SQL), which is disk-based and slow to read and write data. (using the form of two-dimensional table to simplify the data relationship to achieve the processing of data). Commonly used databases are: MySQL, Oracle, MariaDB, sql server, db2

(3) introduction of non-relational database:

   structured query statement that builds a non-relational database on top of a relational database and is used to cache data (data that operates very frequently). Make up for the limitations of relational databases in terms of high IO and high availability. Commonly used databases are: redis, hbase, MongoDB, Neoj4.

2. Installation of MySQL (1) Linux version:

① [hadoop hadoop01@~] $rpm-qa | grep mysql if mysql-server- appears. .x86 _ 64 indicates that it has been installed.

If ② is not installed: yum-y install mysql-server (server side of mysql)

③ starts MySQL:/etc/init.d/mysqld start (default port 3306)

④ setting Boot self-boot chkconfig mysqld on

⑤ modifies the coding of mysql vi / etc/my.cnf

On the next line [mysqld], add: default-character-set=utf-8

(2) installation under Windows

Go to the official website to download an installation package for MySQL under Windows:

Https://dev.mysql.com/downloads/mysql/

Installation:

The rest basically goes straight to next until finish.

Here is a way to retrieve MySQL's forgotten password:

If you installed MySQL under Windows, find a hidden folder programData in mysql /, find my.ini (configuration file for mysql), and add under the [mysqld] tag:

Next: restart MySQL:net start mysql

Then you can enter MySQL directly without using a password.

Finally, in the system table user table of MySQL, change the password of root:

Update user set authentication_string = password ('root') where User='root'