Installation and uninstallation of Ubuntu under MongoDB

This post describes MongoDB and details the reader's installation and use of MongoDB under Ubuntu. This tutorial was tested under Ubuntu14.04.

First, MongoDB Introduction

MongoDB is a database based on distributed file storage, between relational database and non-relational database, the most abundant function of non-relational database, most like relational database. The data structure he supports is very loose and is a JSON-like Bson format, so you can store more complex data types. MONGO's biggest feature is that the query language he supports is very powerful, and its syntax is a bit like an object-oriented query language that almost implements most of the functionality of a relational database single-table query, and also supports indexing of data.

Ii. installation of MongoDB

MongoDB installation is very simple, no need to download the source files, can be installed directly with the Apt-get command.
Open terminal and enter the following command:

sudo apt-get install mongodb

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As follows:

After the installation is complete, enter the following command in the terminal to view the MongoDB version:

mongo -version

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The output version information indicates that the installation was successful, as follows:

Start and close the MongoDB command as follows:

service mongodb startservice mongodb stop

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As follows:

The default setting MongoDB is started automatically with Ubuntu boot.
Enter the following command to see if it started successfully:

-l   #注意：-l是英文字母l，不是阿拉伯数字1

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As follows:

Uninstalling MongoDB

sudo apt-get --purge remove mongodb mongodb-clients mongodb-server

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Third, using the Mongodbshell command mode

Enter the mongo shell command mode, the default connection to the database is the test database, before you must ensure that you have started MongoDB, otherwise there will be an error, after starting to run successfully, as follows:

Common Operation Commands:

Database related
show dbs: Displays the list of databases
show collections: Displays a collection in the current database (similar to tables in a relational database table)
show users: Show All Users
use yourDB: Switch the current database to Yourdb
db.help(): Show Database Operations Command
db.yourCollection.help(): Displays the collection Action command, Yourcollection is the collection name
MongoDB does not have a command to create a database, if you want to create a "School" database, run the use School command first, then do something (such as create a clustered collection db.createCollection(‘teacher‘) ) so that you can create a database called "School". As follows:

The following is an example of a school database in which two sets teacher and student are created in the school database, and the data in the student collection is added and removed for basic operations (Set collection equals table tables in the relational database).
1. Switch to School database

#切换到School数据库。MongoDB 无需预创建School数据库，在使用时会自动创建

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2. Create Collection

db.createCollection(‘teacher‘) #创建一个聚集集合。MongoDB 其实在插入数据的时候，也会自动创建对应的集合，无需预定义集合

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As follows:

3. Inserting data
Similar to database creation, collections are created automatically when data is inserted.
There are two ways of inserting data: Insert and save.

db.student.insert({_id:1, sname: ‘zhangsan‘, sage: 20}) #_id可选db.student.save({_id:1, sname: ‘zhangsan‘, sage: 22}) #_id可选

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In both of these ways, the _id field in the inserted data is not writable, and a unique _id is automatically generated to identify this piece of data. The difference between insert and save is that when you manually insert the _id field, if _id already exists, insert does not do the action, save does the update, and if you do not add the _id field, the same effect is to insert the data. As follows:

The added data is loosely structured, and the column properties are not fixed as long as the Bson format is available, whichever is added. Once you have defined the data, you can insert more than one data at a time, as follows:

After running the above example, student has been created automatically, which also shows that MongoDB does not need to pre-define collection, collection will be created automatically after the data is inserted for the first time. As follows:

3. Find data
db.youCollection.find(criteria, filterDisplay)
Criteria: query criteria, optional
Filterdisplay: Filter Displays part of the data, such as displaying the specified column data, optional (when selected, the first parameter can not be omitted, if the query condition is empty, {} can be used as a placeholder, the following example of the third sentence)

Db.student.find () #查询所有记录. Equivalent to: SELECT * from Studentdb.student.find ({sname:  ' Lisi '}) # Query sname= ' Lisi ' records. Equivalent to: SELECT * from student where sname= ' Lisi ' Db.student.find ({},{sname:1, Sage:1}"  #查询指定列sname, sage data. Equivalent to: Select Sname,sage from student. Sname:1 means that the sname column is returned, and the default _id field is returned, and you can add _id:0 (meaning not to return _id) as {sname:1, sage:1,_id:0}, and the default _id field is not returned Db.student.find ({ Sname:  ' Zhangsan ', Sage: 22})  #and With a conditional query. Equivalent to: SELECT * FROM student where sname = ' Zhangsan ' and sage = 22db.student.find ({ $or: [{sage: 22}, {sage: 25}]})  #or condition query. Equivalent to: SELECT * FROM student where Sage = $ or sage = +             

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The query operation is similar, here only db.student.find({sname: ‘lisi‘}) the query, as follows:

4. Modify the data
db.youCollection.update(criteria, objNew, upsert, multi )
Criteria:update query conditions, similar to those in the SQL update query
Objnew:update objects and some updated operators (such as $set ), etc., can also be understood as SQL update queries within the set.
Upsert: If there is no record of update, insert objnew,true as INSERT, default is False, do not insert.
Multi:mongodb default is False, only update the first record found, if this parameter is true, the condition is checked out all the records are updated. The default is false to modify only the first data that matches to.
Where criteria and objnew are required parameters, Upsert and multi optional Parameters
Examples are as follows:

‘lisi‘}, {$set: {sage: 30}}, false, true) #相当于：update student set sage =30 where sname = ‘lisi‘;

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The operation is as follows:

5. Delete data

‘chenliu‘}) #相当于：delete from student where sname=‘chenliu‘

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The operation is as follows:

6. Exit Shell Command mode
Enter exit or Ctrl+C exit shell command mode

Installation and uninstallation of MongoDB under Ubuntu