MySQL Default INFORMATION_SCHEMA, MySQL, and TEST database usage

The first database INFORMATION_SCHEMA: provides a way to access database metadata.

Metadata is data about data, such as database name or table name, column data type, or access permission. In some cases, other terms used to express this information include "Data Dictionary" and "system directory ".

INFORMATION_SCHEMA is an information database that stores information about all other databases maintained by the MySQL server. There are several read-only tables in INFORMATION_SCHEMA. They are actually views rather than basic tables, so you won't be able to see any files related to them.

Each MySQL user has the right to access these tables, but is limited to specific rows in the Table. Such rows contain objects that the user has the right to access.

Many people now use phpmyadmin to manage mysql databases. Sometimes they do not want common users to see the INFORMATION_SCHEMA database through phpmyadmin. You can set it.

Set this sentence in config. inc. php (some are config. default. php ).

$ Cfg ['servers'] [$ I] ['hide _ db'] = 'information _ scheme ';

SQLyog setting method: when setting the user name and password, there is a DataBase (s) in which you can specify the db you want to access. In this way, you can only read one file. I don't know if the separator ";" will take effect. I haven't tried it.

MySQL-front Setting Method: If this client does not want to see this "information_schema", under the configured Login tab, there is also a DataBase under the user name and password, which can be specified.

Mysql: this is the core database of mysql, similar to the master table in SQL server, it is mainly responsible for storing the control and management information required by mysql, such as database users, permission settings, and keywords. It cannot be deleted. If you are not familiar with mysql, do not modify the table information in the database easily.

The third database is test: A test database created during installation. It is named like a completely empty database and can be deleted without any tables.