Mysql uses commands to implement hierarchical search help

This article mainly introduces to you the relevant information about how Mysql uses commands to achieve hierarchical search help. The sample of this article is based on the branch version of msql MariaDB-10.1.19. The article introduces it in detail through the example code. It is very useful for everyone to learn or Using mysql has certain reference learning value. Friends who need it can follow the editor to learn together. Hope it helps everyone.

Query all help

If we want to know what help mysql can provide us, we can use the following command

? contents

or replace ? with help, The two have the same effect

help contents

The effect is as shown below

? is equivalent to help. For simplicity, we use ? below, but readers need to know if we use help The same effect

Explanations

##English中文ExplanationAccount ManagementAccount ManagementAdministrationManagement##Compound Statements##Data DefinitionData DefinitionData ManipulationData TypeFunctions are usually non-sql standard original commands provided only by this product and similar series of productsGroup functions and modificationsDistributed Features##Help MetadataPlugin Stored Procedure Storage Engine##Table Maintenance##User-Defined FunctionsUser-defined functionsUtilityOther helpView help hierarchicallyThe effect is as follows Figure

Complex Statement
			##Data Manipulation
			Data Types
			##Functions
			Functions and Modifiers for Use with GROUP BY
			Geographic Features
			Metadata
		##Language Structure	Language Structure
		##Plugins
		Procedures
		Storage Engines
		TableMaintenance
	##Transactions	Transaction
		I can’t understand the Chinese meaning here specifically, but I suggest readers to execute ? utility to see the help it can provide
		Now we know what types of help can be found, at this time , we can use question mark + space + specific name to be found for different projects == case-insensitive ==	For example, I want to find out which data types are supported ? data type

There are many data types. Usually we may only use char varchar int boolean bit timestamp datetime float, etc., but there are still many we don’t know and rarely use them. , such as: BIGINT, ENUM, BLOB, etc., then when we sometimes involve database optimization, we need to have a deeper understanding of the characteristics of a certain type or want to know whether there is a more suitable data type, then we all Can you use ? to find the corresponding data type

As shown below

So now, we can know that BLOB is a data that can hold 65535 bytes Type

is roughly based on this method, which can save the time of Baidu in actual development and directly find the required help step by step

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