Basic usage skills of MongoDB and mongodb

Basic usage skills of MongoDB and mongodb

This section describes some basic operations of MongoDB.

Create user-specified database login get more command insert document MongDB common query comparison

Create user

> Db. createUser ({user: "<your user name>", pwd: "<your password>", roles: [{role: "readWrite", db: "<the database you want to create>"}]})

Specified database

# For example, if I have created an admin database, the switch mode is> use admin.

Note:Use the use command to specify the database used by Sanjin. If the database does not exist, a new database is created.

Login

> Db. auth ("<account>", "<password> ")

When the console output is1Indicates successful

Get more commands

> db.help()

More commands will be listed.

Insert document

MongoDB manages databases through collections. Similar to database tables, a Collection contains multiple documents, which are similar to the records of database tables. MongoDB does not need to create a set on display. You can add documents to the set directly. For example:

Db. test. insert ({_ id: "springboot", desc: "create distributed server", tag: ["IT", "Spring"],})

Introduction Parameters
_ Id: Fields starting with the line below MongoDB have special meanings, indicating the document's primary keyIf the document does not provide a primary key, the system automatically generates a primary key of the ObjectID type. Desc: Entry description tag: saved as an array. The MongDB field type can be string, number, boolean, date, or document type. Comment: This field is a JSON document. Comparison of common MongDB queries

MongoDB format	Code Format	Instance
$ Gt	>	"Comment. good": {$ gt: 1000} indicates that comment. good is an element greater than 1000.
$ Gte	> =	"Comment. good": {$ gte: 1000}
$ Lt	<	"Comment. good": {$ lt: 1000}
$ Lte	<=	"Comment. good": {$ lte: 1000}
$ Eq	=	"Comment. good": {$ eq: 1000}
$ Ne	! =	"Comment. good": {$ ne: 1000}
$ In	In	"Tag": {$ in: ["IT", "template language"] Find All tags that contain IT and template languages}
$ Nin	Not in	Not in