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MySQL 9.5 Reference Manual

15.8.3 HELP Statement

HELP 'search_string'

TheHELP statement returns online information from the MySQL Reference Manual. Its proper operation requires that the help tables in themysql database be initialized with help topic information (seeSection 7.1.17, “Server-Side Help Support”).

TheHELP statement searches the help tables for the given search string and displays the result of the search. The search string is not case-sensitive.

The search string can contain the wildcard characters% and_. These have the same meaning as for pattern-matching operations performed with theLIKE operator. For example,HELP 'rep%' returns a list of topics that begin withrep.

TheHELP statement does not require a terminator such as; or\G.

TheHELP statement understands several types of search strings:

At the most general level, usecontents to retrieve a list of the top-level help categories:
```
HELP 'contents'
```
For a list of topics in a given help category, such asData Types, use the category name:
```
HELP 'data types'
```
For help on a specific help topic, such as theASCII() function or theCREATE TABLE statement, use the associated keyword or keywords:
```
HELP 'ascii'HELP 'create table'
```

In other words, the search string matches a category, many topics, or a single topic. The following descriptions indicate the forms that the result set can take.

Empty result
No match could be found for the search string.
Example:HELP 'fake'
Yields:
```
Nothing foundPlease try to run 'help contents' for a list of all accessible topics
```

Result set containing a single row

This means that the search string yielded a hit for the help topic. The result includes the following items:

name: The topic name.
description: Descriptive help text for the topic.
example: One or more usage examples. (May be empty.)

Example:HELP 'log'

Yields:

Name: 'LOG'Description:Syntax:LOG(X), LOG(B,X)If called with one parameter, this function returns the naturallogarithm of X. If X is less than or equal to 0.0E0, the functionreturns NULL and a warning "Invalid argument for logarithm" isreported. Returns NULL if X or B is NULL.The inverse of this function (when called with a single argument) isthe EXP() function.URL: https://dev.mysql.com/doc/refman/8.4/en/mathematical-functions.htmlExamples:mysql> SELECT LOG(2);        -> 0.69314718055995mysql> SELECT LOG(-2);        -> NULL

List of topics.

This means that the search string matched multiple help topics.

Example:HELP 'status'

Yields:

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:   FLUSH   SHOW   SHOW BINARY LOG STATUS   SHOW ENGINE   SHOW FUNCTION STATUS   SHOW PROCEDURE STATUS   SHOW REPLICA STATUS   SHOW STATUS   SHOW TABLE STATUS

List of topics.

A list is also displayed if the search string matches a category.

Example:HELP 'functions'

Yields:

You asked for help about help category: "Functions"For more information, type 'help <item>', where <item> is one of the followingcategories:   Aggregate Functions and Modifiers   Bit Functions   Cast Functions and Operators   Comparison Operators   Date and Time Functions   Encryption Functions   Enterprise Encryption Functions   Flow Control Functions   GROUP BY Functions and Modifiers   GTID   Information Functions   Internal Functions   Locking Functions   Logical Operators   Miscellaneous Functions   Numeric Functions   Performance Schema Functions   Spatial Functions   String Functions   Window Functions   XML

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