"MongoDB Tutorial Lesson Four" MongoDB Create a collection

Reatecollection () method

MongoDB db.createcollection (name, options) is used to create collections.

Grammar:

The basic createcollection () command syntax is as follows:

DB.  CreateCollection(name, options)      

In the commands, name is the name of the collection to be created. Options is a file that specifies a collection of configurations

Parameters	type	Description
Name	String	The name of the collection to create
Options	Document	Optionally, specify the memory size and index options

Options?? The parameter is optional, so only the specified collection name is required. The following is a list of options you can use:

Field	type	Description
Capped	Boolean	(optional) If true, the CAP collection is enabled. A capped collection is a fixed-size collection that automatically overwrites the oldest entry when it reaches its maximum size. If True is specified, the dimension parameter needs to be specified as well.
Autoindexid	Boolean	(optional) If true, the default value for the auto-create index _id field is false.
Size	Number	Optionally, specify a maximum size byte capping set. If the cap is true, then you also need to specify this field.
Max	Number	Optionally, specify the maximum number of files allowed in the capping collection.

When inserting a document, the MongoDB first check Size field caps the collection, and then it checks the largest field.

Example:

The basic syntax for the CreateCollection () method to not use options is as follows:

>use testswitched to db Test>db.  CreateCollection("mycollection"){"OK":1}>    

You can check the Create collection command by using show collections

>show Collectionsmycollectionsystem.  Indexes  

The following example shows several important options for the syntax of the CreateCollection () method:

>Db.CreateCollection("MyCol", { capped : true, Autoindexid : true, size : 6142800 , Max : 10000  } ) {< Span class= "PLN" >  "OK"  :  1 }>      

In MongoDB, you do not need to create a collection. When inserting some files MongoDB automatically creates the collection.

>db.  Yiibai.  Insert({"name":"Yiibai"})>show Collectionsmycolmycollectionsystem.  Indexesyiibai>              

"MongoDB Tutorial Lesson Four" MongoDB Create a collection