Basic Commands
In this note
collection = table
document = row
object = key
attribute = value
(1) Insert document
(1) db.collection.insert ({}) #insert
one or more documents
> db.test.insert({
_id:1,name:'zbj',
age:18,
addres:'zhu'
})
WriteResult({ "nInserted" : 1 }) ##插入一个或多个文档
(2) db.collection.insertOne ({}) #When
filling in multiple documents at the same time, only the first document will be inserted
(3) db.collection.insertMany ([{}, {}])
#Only allow multiple documents to be inserted
> db.test.insertMany([{
"_id" : 2,
"name" : "zbj",
"age" : 18,
"addres" : "zhu" },
{ "_id" : 4,
"name" : "zbj",
"age" : 18,
"addres" : "zhu"}
])
(4) Define variables
> document=({title: 'MongoDB',
by: 'cc',
url: 'www',
tags: ['mongodb', 'database', 'NoSQL'],
});
(5) Then perform the insert operation
db.test.insert(document)
(Two) query documents
(1) db.collection.find () #Find
all documents by default
Note: find () returns an array, that is, you can search by index
db.test.find()[0]
db.collection.find ({Condition 1, Condition 2})
#Condition query (and)
db.test.find({_id:'1'})
(2) db.collection.findOne () #Query
the first document
that meets the conditions Note: The document object returned
(3) db.collection.find ({}). The function
skip () skips the specified amount of data
lilmit () to limit the number of items displayed on each page
.
db.collection.find( { } ).count() #文档数
db.collection.find( { } ).length() #同上
db.qq1.find().skip(10).limit(10) #跳过前十条查询接下来的十条
Conditional query
For example, find documents with num greater than 200 and less than 300
db.test.find({num:{$gt:200,$lt:300}});
(3) Modify the document
(1) db.collection.update ({query object and attribute}, {replacement object and attribute})
#The latter document will replace all the documents queried by the former, and
only useful for the first document queried
db.test.update({
_id:'1'},
{name:'5',
home:'2'
})
(2) db.collection.save ({replace content}) #Replace
all content in the collection
(3) db.test.replaceOne ({name: "cgp"}, {name: "cgp240"})
db.test.replaceMany ({name: "cgp"}, {name: "cgp240"}) to
replace the specified content
To modify specified objects or attributes, use the "modify operator":
(1) $ set
Note that if the specified object does not exist, a new object will be added. Update () only modifies the first matching document by default, and modifying multiple ones requires updateMany ()
db.test.update({
查询对象},
{$set{
指定对象替换
}}) #不能用于添加属性
#Delete the specified object $ unset
db.test.update({
查询对象},
{$unset{
指定对象
}})
(2) $ push: you can add
$ addToset: do not add existing attributes
to add attributes to the array
>{ "_id" : ObjectId("5e8d7a48315dd25b1a6d92c5"),
"name" :{ "test" : [ 1, 2, 3, 4] },
"home" : "湖南" }
>db.test.update({
home:"湖南"},
{$push:{"name.test":5
}})
(3) The document attribute of Mongodb can be a document
When the attribute of a document is a document, the document is called an embedded document
db.test.update({
name:"240"},
{$set:{name:{"ming":"陈哥"}
}});
Inline document query method: db.xxx.find ({"first object. Second object": "attribute"})
db.test.find({"name.ming":"陈哥"})
(4) Delete the document
db.collection.remove ({}) #Delete
all documents that meet the conditions by default
db.collection.remove ({}, true) #Delete
the first document that meets the conditions
db.collection.deleteOne ({}) #Delete
the first document that meets the conditions
db.collection.deleteMany ({}) #Delete
all documents that meet the conditions
Empty collection
db.collection.drop()
