Shulou(Shulou.com)05/31 Report--

It is believed that many inexperienced people have no idea about how to install and use pymongo in mongodb. Therefore, this article summarizes the causes and solutions of the problem. Through this article, I hope you can solve this problem.

(1) installation of mongodb

After downloading and decompressing the tgz, you need to add the corresponding environment variables to start the mongod directly on the terminal.

Mongodb data is stored in / data/db, so you need to create a directory tree manually, and if you don't have enough permissions to execute mongod (you can't write to / data/db), you need to change the permissions.

Vim ~ / .bashrcexport PATH= "~ / download/mongodb-linux-x86_64-ubuntu/bin:$PATH" mkdir-p / data/dbls-l / View the permissions of the data directory, find that the owner can write ls-l / data to view the permissions of the db directory, and find that the owner can write all the files under chown-R "liaohuqiang" / data data instead.

(2) start of mongod

After that, you can type mongod on the terminal, and mongodb is started at this time, but at this time it is running on the terminal, which is equivalent to a foreground process, and you cannot do anything else on this terminal.

You can use the-- fork option, and when enabled, you will go back to the terminal to interact and continue to do your own things.

Fork means to start mongodb as a daemon to create a server process. Fork is used with logpath to indicate the log file to which the log information is output. Logappend means to write to the log file as an append.

Of course, there are other ways to start, which are not used yet, so let's not talk about it for the time being.

Mongod-fork-logappend ~ / mongo.log-logappend

(3) the use of mongo

After starting mongod, you can enter mongo at the terminal for related database operations.

Show dbs displays all database use doctor switches to a database "doctor". If not, the default is to use testdb.dropDatabase () delete database show collections display all collections db.sample.drop () delete collections db.sample.insert ({name: "pilgrimHui", label: "1"}) insert a row of records db.sample.insert ({...}) if the document already exists, update _ id If it does not exist, search for records that meet the conditions with insertdb.sample.find ({...}). For some simple query conditions, see db.sample.find ({...}, {field1:1, field2:1}) below. Only find some fields db.sample.find () find all records in the sample collection db.sample.remove ({...}, 1) delete records that meet the criteria. Parameter 1 is optional. Means to delete only 1 db.sample.remove ({}) to delete all records in the sample collection

(4) update operation in mongo

Db.collection.update (criteria, objNew, upsert, multi) criteria: query condition, which is understood as the objNew: update operation after the sql update statement where, and as the upsert after the sql update statement set: whether to insert the query record if it does not exist. Default false, do not insert multi: whether to update multiple entries. By default false, only the first entry is updated. # for example: change the status of all records in the collection to 0db.sample.update ({"status": {$ne: 0}}, {$set: {"status": 0}}, {multi: true}) or db.sample.update ({"status": {$ne: 0}}, {$set: {"status": 0}}, false,true)

(4) several query operators

$ne unequal $gt greater than $gte greater than or equal to $lt less than $lte less than or equal to $in and whether $nin is in the specified array whether $all is all in the specified array $or pairs or operates on multiple keys in the array $slice: [1] slice, take some $size of the attribute value (array) the length of the attribute value (array) $exists:true Select the record that exists in this field $not take any query operator non-$regex use regular expression matching

(5) several update operators

{$inc: {field: value}} {$set: {field: value}} {$unset: {field: 1}} {$push: {field: value}} append Field if the array {$pull: {field: value}} is the opposite of push {$pop: {field: 1}} delete the last value {$pop: {field:-1}} delete the first value {$currentDate: {: {$type: "date",.}} set the current time {$rename: {:,.}} rename the field

(6) user permission setting

Mongodb does not have an account to log in by default. You need to add your own account first.

The account added in the admin database is the administrator account, and the account added in other databases is ordinary users.

Users can only log in in the database where the user resides, including administrators.

Administrators can manage other databases only after admin login authentication.

6.1 add administrator account

Use admindb.system.users.find ()

Db.addUser ('liaohuqiang','liaohuqiang') add an administrator user. If the version of mongodb is different, an error may be reported. If the error is reported, the addUser cannot be found.

Use this one below

Db.createUser ({user: 'liaohuqiang', pwd:' liaohuqiang', roles: [{role: "userAdminAnyDatabase", db: "admin"}]})

6.2 restart mongod

Restart mongod after a successful creation. When you open the connection, you can use the-- auth option to verify the user permissions.

Mongod-fork-logappend ~ / mongo.log-logappend-auth

6.3 Authentication login

When enabled, direct mongo access will be restricted. Login can be authorized when mongo is connected, or authentication can be performed after connecting to it.

Mongo-u liaohuqiang-p-- authenticationDatabase adminmysql-h ip-u root-p intrusions, compare mysql's connection mongouse admindb.auth ('liaohuqiang',' liaohuqiang')

6.4 close the connection

After authentication and login, you can operate the database as before, and after the operation, you can close the connection in the admin database.

Use admin db.shutdownServer () closes mongod

(7) connection of pymongo

Import pymongoclient=pymongo.MongoClient ('mongodb://username:password@ip') db=client [' doctor'] users=db ["user"] result= list (users.find ({'role':1}, {' _ id':0})) Select multiple result= users.find_one ({"name": name}) choose a single users.insert_one ({"name": name}) insert one Will automatically generate primary key users.remove ({"name": name}, {"multi": True}) delete multiple users.update_one ({'name':name}, {' $inc': {'commitCount':1}}) after reading the above content, have you mastered how to install and use pymongo in mongodb? If you want to learn more skills or want to know more about it, you are welcome to follow the industry information channel, thank you for reading!

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.