MongoDB basic Commands

MongoDB Basic Commands

After the MongoDB is successfully started, you can then open a command line window to enter MONGO to perform some operations on the database.

Enter help to see basic operations commands:

Show DBS: Displaying a list of databases
Show Collections: Displays the collection in the current database (similar to tables in a relational database)
Show Users: displaying user

Use <db name>: Toggle the current database, which is the same as in Ms-sql.
Db.help (): Display database operation commands, there are a lot of commands
Db.foo.help (): Displays the set Operation command, also has a lot of commands, Foo refers to the current database, a collection called Foo, not the true meaning of the command
Db.foo.find (): Data lookup for the Foo collection in the current database (all data is listed because there are no conditions)
Db.foo.find ({a:1}): Finds a collection of Foo in the current database, provided that one of the properties in the data is called a, and A has a value of 1

Database Common Commands

1. Help View command Prompt

     
     
      
       Help
      
        Db.help ();
      
        Db.yourColl.help ();
      
        Db.youColl.find (). Help ();
      
        Rs.help ();
     
     

2. Switch/CREATE Database

Use Yourdb; The current database is created automatically when a collection (table) is created

MongoDB does not have a command to create the database, but has a similar command.

For example, if you want to create a "myTest" database, run the use myTest command before inserting some data into the Runoob database.

For example

Instance the following instance we created the database Runoob: > Use Runoob switched to D  b runoob > DB runoob > If you want to view all databases, you can use show DBS 
      
      

      
      Command: > Show dbs local 0.078GB test 0.078GB >
      
      

      
      As you can see, the database we just created Runoob is not in the list of databases, and to show it, we need to insert some data into the Runoob database.
      
      > Db.runoob.insert ({"Name": "Rookie Tutorial"}) Writeresult ({"ninserted": 1}) > show DBS 
      
      

      
      Local 0.078GB runoob 0.078GB Test 0.078GB > The default database in MongoDB is test, and if you do not create a new database, the collection will be stored in the test database.

3, query all databases

Show DBS;

4, delete the current use of the database

Db.dropdatabase ();

5. Collection (document)

5.1 Deleting a collection

Db.collection.drop ()

The following instance deletes the collection site from the Runoob database:

> Use Runoob
switched to DB Runoob
> Show Tables
site
> Db.site.drop ()
true
> Show Tables
> 

6. Document

The data structure of the document is basically the same as that of JSON.

All data stored in the collection is in Bson format.

Bson is a binary form of class JSON storage format, referred to as binary JSON.

6.1 Creating a Document

Format

Db. Collection_name.insert (document)   if the collection is not in the database, MongoDB automatically creates the set and inserts the document.

Example

Db.col.insert ({title: ' MongoDB Tutorial ', Description: ' MongoDB is a Nosql database ', by: ' Rookie tutorial ', url: ' Http://www.runoob . com ', Tags: [' mongodb ', ' database ', ' NoSQL '], likes:100})
We can also define the data as a variable, as follows:
     
     

     
     
>document= ({title: ' MongoDB Tutorial ', 
    Description: ' MongoDB is a Nosql database ', by
    : ' Rookie tutorial ',
    URL: ' http:// Www.runoob.com ',
    Tags: [' mongodb ', ' database ', ' NoSQL '],
    likes:100
});
     
     
To perform an insert operation:
> Db.col.insert (document)
Writeresult ({"ninserted": 1})

      
      
       
       

      
      
    
    

Insert document You can also use the Db.col.save command. If you do not specify the _id field Save () method is similar to the Insert () method. If you specify a _id field, the data for that _id is updated.
View the inserted document

Db.col.find ()

6.2, update the document updated format

Db.collection.update (
   <query>,
   <update>,
   {
     upsert: <boolean>,
     Multi: < Boolean>,
     writeconcern: <document>
   }
)

The

parameter description: query  : The query criteria for update, similar to those in the SQL update query. update  : The object of the update and some updated operators, such as $, $inc ... , and so on, can also be understood as upsert  after set in SQL Update query: Optional, this argument means that if there is no record of update, insert objnew,true as INSERT, The default is false, not inserted. multi  : Optional, mongodb default is False, only the first record found is updated, and if this argument is true, multiple records are updated as conditions are checked. writeconcern  : Optionally, the level at which the exception is thrown. For example,