mongodb basic addition, deletion, modification, and query operations

mongodb

• The default port number of MYSQL: 3306

• The default port number of Mongodb: 27017

  NOSQL non-relational database management system

  Used for ultra-large-scale data storage (eg: Google, Facebook) does not require a fixed model, and can be scaled horizontally without unnecessary operations

What is MongoDB?

Written in C++, it is an open source database system based on distributed file storage.

In the case of high load, adding more nodes can ensure server performance.

• Provide scalable high-performance data storage solutions for WEB applications
• MongoDB data is stored as a document, and the data structure is composed of key-value (key=>value) pairs
• MongoDB documents are similar to JSON objects, and the field values ​​can include other documents, arrays and document arrays

Concept analysis

SQL	MongoDB	explain
table	collection	set
row (one row, one record)	document	Documentation
column	field	Domain (key-value pair)
index	index	index
table joins		Table connection query is not supported
primary key	primary key	Primary key, mongoDB automatically sets the _id field as the primary key

database

db. Different databases are placed in different files

show dbs can display a list of all databases

data storage name:

Cannot be a character string (""), no spaces, .,,/,\0 (empty characters) It is best not to use Chinese (Chinese garbled characters may occur), all lowercase, up to 64 bytes

Documentation:

Key-value pair, BSON

{”site":"xxxxx"，"age":25}

Database service and client
MYSQL/Oracle	mongod

note:

• The key-value pairs in the document are ordered
• Type and case sensitive
• There can be no duplicate keys,
• Key: string (utf-8), cannot contain empty characters
• . $ Has a special meaning, only used in a specific environment
• The key at the beginning of _ is reserved (not strictly required)

object

onject_id can be of any type, generally the default is object type

The created timestamp is saved in onject_id, so there is no need to create timestamp by yourself (timestap)

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Get the creation time of the document through the getTimestap function

Convert to string form by str

date

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Basic operations of MongoDB

One, create a database

use xxx

But there is no content in the database, it will be displayed after inserting the content

Two, delete the database

db.dropDatabase()

Switch to another database to see that it has been deleted

Three, create a collection

• db.createCollection("employee") creates a collection of employee
• db.mycol(collection name).insert({"_id":01,"name":"马云"}) Insert directly, there is no collection will automatically create a mycol collection
• show collections show the collections under the database
• db view the current database

Fourth, delete the collection

db.tc (collection name).drop()

Five, insert documents into the collection

db.collection name.insert(document) If _id exists, the primary key exception will be thrown and the current data will not be saved

db.collection name.save(document) If _id exists, update the data, if it does not exist, insert the data

Insert a record

var document name = db.collection name.insert({insert key-value pair content})

Insert multiple records

var document name = db.collection name.insertOne({})

Insert multiple documents

var document name = db.collection name.insertMany({})

Insert array

1. Create an array first

Sixth, the update of the document

db.collection name.updata(

{query—query condition}

upsert–true: insert if it does not exist, update if it exists, false: do not update

{$set"{updated value}}—why update value

multi:true/false—true: update all qualified values, false: update only the first qualified value

)

Update a value

db.employee.update({“sex”:“男”},{$set:{“age”:18}})

All updates that meet the conditions

db.employee.update({“sex”:“男”},{$set:{“age”:18}},{multi:true})

Seven, document query

1. Condition mark

$gt	>
$gte	>=
$lt	<
$ lte	<=
$ do	!=
$eq	、=

Query records whose age is less than 19

Query records whose age is less than or equal to 19

Check if the age is less than 30 and the address is in Yan'an

db.employee.find({“age”:{$lt:20},“address”:“延安”})

2. AND OR condition

AND

db.employee.find({'KaTeX parse error: Expected '}', got 'EOF' at end of input: and':[{"age":{ lt:20}},{“address”:“延安”}]})

'$and'-and relational character

[{Condition 1}, {Condition 2}]

OR

db.employee.find({'KaTeX parse error: Expected '}', got 'EOF' at end of input: or':[{"age":{ lt:20}},{“address”:“延安”}]}))

db.employee.find({"KaTeX parse error: Expected '}', got 'EOF' at end of input: …":"女"},{"age":{ gt:10}}]})

Gender is female, age>10

Query on robo 3T

AND and OR combined

First and then or

db.employee.find({“sal”:{ KaTeX parse error: Expected 'EOF', got '}' at position 9: gt:17000}̲,'or’:[{“sex”:“女”},{“address”:“延安”}]})

db.employee.find({“sal”:{ KaTeX parse error: Expected 'EOF', got '}' at position 9: gt:19000}̲,"or":[{“sex”:“女”},{“address”:“延安”}]})

db.getCollection('employee').find({"age":{$lt:30},"address":"郑州"})db.employee.find({"age":{$lt:30},"address":"郑州"})

//查询age小于30并且地址是郑州的document
db.employee.find({'$and':[{"age":{$lt:30}},{"address":"郑州"}]}) db.getCollection('employee').find({})

//查询age小于30或address是洛阳document
db.employee.find({'$or':[{"age":{$lt:30}},{"address":"洛阳"}]}) 

//查询sex为女或address是南京的document
db.employee.find({'$or':[{"sex":"女"},{"address":"南京"}]})  

// (price>70 and (publish="机械工业出版社" or public="新疆儿童出版社"))
db.db_book.find({"price":{$gt:70},'$or':[{"publish":"机械工业出版社"},{"publish":"新疆儿童出版社"}]})

8. Fuzzy query

• /content/
• /^ What starts with/
• /Ends with $/

Those with Jiang in their name

db.employee.find({“name”:/蒋/})

start with the word horse in name

db.employee.find({“name”:/^马/})

The name that ends with the word according to

db.employee.find({“name”:/依$/})

Nine, delete documents

db.collection name.remove({specify conditions})

db.employee.remove({_id:1002})  删除_id为1002的文档

db.collection name.remove (delete condition, 1)

db.employee.remove({name:/诸/},1)  删除名字中有诸的，并且只删除一个文档

The name that ends with the word according to

db.employee.find({“name”:/依$/})