if you provide an argument to the help command, mysql uses it as a search string to access server-side help from the contents of the MySQL Reference Manual.
https://mysqlserverteam.com/getting-help-in-mysql-shell/ https://dev.mysql.com/doc/refman/5.7/en/mysql-server-side-help.html
Mysql version
mysql> status
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mysql Ver 14.14 Distrib 5.7.23, for Linux (x86_64) using EditLine wrapper
Use help contents to see a list of the help categories:
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
You specify the subtype of the element to get its help
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
The search string can contain the wildcard characters % and _. These have the same meaning as for pattern-matching operations performed with the LIKE operator
mysql> help rep%
Many help items for your request exist.
To make a more specific request, please type 'help <item>',
where <item> is one of the following
topics:
REPAIR TABLE
REPEAT FUNCTION
REPEAT LOOP
REPLACE