MySQL learning notes help document

mysql> help contents;
You asked for help about help category: "Contents"
For more information, type 'help <item>', where <item> is one of the following
categories:
  Account Management
  Administration
  Compound Statements
  Data Definition
  Data Manipulation
  Data Types
  Functions
  Functions and Modifiers for Use with GROUP BY
  Geographic Features
  Help Metadata
  Language Structure
  Plugins
  Procedures
  Storage Engines
  Table Maintenance
  Transactions
  User-Defined Functions
  Utility

mysql> help data types;
You asked for help about help category: "Data Types"
For more information, type 'help <item>', where <item> is one of the following
topics:
  AUTO_INCREMENT
  BIGINT
  BINARY
  BIT
  BLOB
  BLOB DATA TYPE
  BOOLEAN
  CHAR
  CHAR BYTE
  DATE
  DATETIME
  DEC
  DECIMAL
  DOUBLE
  DOUBLE PRECISION
  ENUM
  FLOAT
  INT
  INTEGER
  LONGBLOB
  LONGTEXT
  MEDIUMBLOB
  MEDIUMINT
  MEDIUMTEXT
  SET DATA TYPE
  SMALLINT
  TEXT
  TIME
  TIMESTAMP
  TINYBLOB
  TINYINT
  TINYTEXT
  VARBINARY
  VARCHAR
  YEAR DATA TYPE

mysql> help int;
Name: 'INT'
Description:
INT[(M)] [UNSIGNED] [ZEROFILL]
A normal-size integer. The signed range is -2147483648 to 2147483647.
The unsigned range is 0 to 4294967295.
URL: http://dev.mysql.com/doc/refman/5.7/en/numeric-type-overview.html
mysql> help tinyint;
Name: 'TINYINT'
Description:
TINYINT[(M)] [UNSIGNED] [ZEROFILL]
A very small integer. The signed range is -128 to 127. The unsigned
range is 0 to 255.
URL: http://dev.mysql.com/doc/refman/5.7/en/numeric-type-overview.html