SQL database in information_scheme
The default generated database, which holds information on all of the SQL databases.
information_schema the important tables and tables of important fields
SCHEMATA：
It provides information on all the current mysql database is the result of the show databases
Schema_name: database name
Default_Character_Set_Name: the default character encoding
TABLES：
Providing information about the current database tables (including views), describes a Schema belong to a table, the result of the show tables from schemaname.
TABLES_SCHEMA: the name of the database table belongs
TABLES_NAME: Table Name
COLUMNS：
It provides information about the current column.
TABLE_SCHEMA: a column in your database
TABLE_NAME: a column belongs
COLUMN_NAME: a column Column Name
