Introduction to MySQL default database

Similar to large databases such as MS SQL Server, MySQL databases also provide built-in databases, which are:

INFORMATION_SCHEMA

Mysql

Test

1.information_schema

The first database, INFORMATION_SCHEMA, provides a way to access database metadata. Metadata is data about data, such as database or table names, data types of columns, or access permissions. Sometimes other terms used to describe this information include "data dictionary" and "system catalog".

INFORMATION_SCHEMA is an information database that holds information about all other databases maintained by the MySQL server. In INFORMATION_SCHEMA, there are several read-only tables. They are actually views, not basic tables, so you won't be able to see any files associated with them.

Each MySQL user has access to these tables, but only to specific rows in the table that contain objects for which the user has the appropriate access rights.

Nowadays, many people use phpmyadmin to manage mysql databases, and sometimes they don't want ordinary users to see INFORMATION_SCHEMA databases through phpmyadmin. We can set it like this:

Set this sentence in config.inc.php (there are plenty of config.default.php)

$cfg ['Servers'] [$I] [' hide_db'] = 'information_schema'

2.mysql

The second database mysql: this is the core database of mysql, which is similar to the master table in sql server. It is mainly responsible for storing the control and management information that mysql needs to use, such as database users, permissions settings, keywords and so on. Can not be deleted, if you do not know much about mysql, do not easily modify the table information in this database.

3.test

The third database is test: this is a test database created during installation, which, like its name, is a completely empty database with no tables and can be deleted.