MongoDB document deletion and mongodb document deletion skills

MongoDB document deletion and mongodb document deletion skills

? ? The MongoDB remove () function is used to remove data from the set.

? ? You can use the update () function to update MongoDB data. It is a good habit to execute the find () command before executing the remove () function to determine whether the execution conditions are correct.

Syntax

? ? The basic syntax format of the remove () method is as follows:

db.collection.remove(   
 
  ,   
  
   )
  
 

? ? If your MongoDB version is later than 2.6, the syntax format is as follows:

db.collection.remove(   
 
  ,   {     justOne: 
  
   ,     writeConcern: 
   
       })
   
  
 

Parameter description:

? ? · Query: (optional) Conditions for deleting objects.

? ? · JustOne: (optional) Delete only one document if set to true or 1.

? ? · WriteConcern: (optional) exception level.

Instance

? ? We perform the following two insert operations:

> Db. col. insert ({title: 'mongodb ', description: 'mongodb is a Nosql database', by: 'cainiao ', url: 'https: // www.runoob.com ', tags: ['mongodb ', 'database', 'nosql'], likes: 100 })

? ? Use the find () function to query data:

> Db. col. find () {"_ id": ObjectId ("56066169ade2f21f36b03133"), "title": "MongoDB tutorial", "description": "MongoDB is a Nosql Database ", "by": "cainiao tutorial", "url": "https://www.runoob.com", "tags": ["mongodb", "database", "NoSQL"], "likes ": 100} {"_ id": ObjectId ("5606616dade2f21f36b03138"), "title": "MongoDB tutorial", "description": "MongoDB is a Nosql Database", "": "cainiao tutorial", "url": "https://www.runoob.com", "tags": ["mongodb", "database", "NoSQL"], "likes": 100}

? ? Next, we will remove the tilte document "MongoDB tutorial:

> Db. col. remove ({'title': 'mongodb tutorial '}) WriteResult ({"nRemoved": 2}) # two data items are deleted> db. col. find ()...... # No data

? If you only want to delete the first record, set justOne to 1, as shown below:

>db.COLLECTION_NAME.remove(DELETION_CRITERIA,1)

? ? To delete all data, use the following methods:

>db.col.remove({})>db.col.find()>

Note list

? ? The remove () method is outdated. Currently, the deleteOne () and deleteMany () methods are recommended.

? ? For example, to delete all documents under a collection:

db.inventory.deleteMany({})

? ? Delete all documents whose status is equal to:

db.inventory.deleteMany({ status : "A" })

? ? Delete a document whose status is D:

db.inventory.deleteOne( { status: "D" } )