Detailed description of Python3 simple and easy-to-understand Mongodb tutorial, detailed description of python3mongodb

Detailed description of Python3 simple and easy-to-understand Mongodb tutorial, detailed description of python3mongodb

Connect to database

To connect to a database, you must provide an address and interface. First, import the package.

from pymongo import MongoClientconn = MongoClient('localhost',27017)

Of course, you can write as follows:

conn = MongoClient('mongodb://localhost:27017/')

Create a database

Mongodb does not need to create a database in advance, but is directly used. If it is not found, it is automatically created.

db = conn.testdb

The preceding statement creates a database named testdb. However, when no data is inserted, you cannot see the database in the management tool (not displayed ).

Insert data

First, insert a piece of data.

Insert a single record

From pymongo import Export clientconn = MongoClient ('mongodb: // localhost: 27017/') db = conn. testdbdb. col. insert ({"name": 'anying', 'vince ': 'jiangsu', 'age': 25 })

Note: In the following operations, the database connection operation will be ignored and the core code will be directly written. Please complete the operation yourself.

The python Console does not happen, which means success. Using management tools to view database records does contain a piece of data.

Insert multiple records

Mongodb can also insert multiple data records at a time.

Db. col. insert ([{"name": 'anying', 'province ': 'jiangsu', 'age': 25}, {"name": 'zhang san', 'province ': 'zhejiang ', 'age': 24}, {"name": 'zhang San 1', 'vince': 'zhejiang 1', 'age': 25 }, {"name": 'zhang San 2', 'province ': 'zhejiang 2', 'age': 26 },{ "name": 'zhang San 3', 'province ': 'zhejiang 3', 'age': 28},])

Query data

Next we will query the inserted data.

Single Query

We can use find_one () to query a record.

db.col.find_one()

The preceding statement can query a mongodb record. The _ id in the record is the unique value automatically generated by Mongodb.

Copy codeThe Code is as follows:
{'_ Id': ObjectId ('5925351ad92fac3250b9ae3f'), 'name': 'anying', 'province': 'jiangsu ', 'age': 25}

We can insert some data for the following operations. (Omitted tens of thousands of characters)

Query all

If we need to query all records, we can use db. col. find () but we can find a result resource set.

We can use for to list all records.

for item in db.col.find(): print(item)

In this way, all records can be obtained.

{'_ Id': ObjectId ('5925351ad92fac3250b9ae3f'), 'name': 'anying', 'province': 'jiangsu ', 'age ': 25} {'_ id': ObjectId ('592550e5d92fac0b8c449f87'), 'name': 'hangsan ', 'province': 'beijing', 'age ': 29} {'_ id': ObjectId ('592550f6d92fac3548c20b1a'), 'name': 'lisi', 'province ': 'shanghai', 'age ': 22} {'_ id': ObjectId ('59253478d92fac43dcb%a'), 'name': 'wang binm', 'province': 'guangdong ', 'age': 30}

Conditional Query

You can filter data by inserting the query conditions as parameters.

for item in db.col.find({'name':"yanying"}): print(item)

Query Result

Copy codeThe Code is as follows:
{'_ Id': ObjectId ('5925351ad92fac3250b9ae3f'), 'name': 'anying', 'province': 'jiangsu ', 'age': 25}

Of course, you can also query records smaller than a specific value.

for item in db.col.find({"age":{"$lt":25}}): print(item)

Or a record greater than a specific value

for item in db.col.find({"age":{"$gt":25}}): print(item)

Statistics Query

The above code can calculate the number of all records

db.col.find().count() // 4

Or add some conditions.

db.col.find({"age":{"$gt":25}}).count() //2

Query records by _ id

_ Id is the id automatically generated by mongodb. Its type is ObjectId. to use it, you need to convert the type.

This method is provided in python3, but a library needs to be imported.

from bson.objectid import ObjectId

In this way, you can directly use _ id for query.

collection.find_one({'_id':ObjectId('592550e5d92fac0b8c449f87')})

Result sorting

You only need to put the fields to be sorted into the sort method. Mongodb is in ascending order by default.

db.col.find().sort("age")

However, you can add some parameters to change the sorting method. For example, in reverse order, remember to import the pymongo Library first.

import pymongodb.col.find().sort("UserName",pymongo.DESCENDING)

You can also sort it in ascending order, though this is the default case.

for item in db.col.find().sort('age',pymongo.ASCENDING): print(item)

Update Data

Updating data is simple. You only need one condition and the data to be updated.

Copy codeThe Code is as follows:
Db. col. update ({'_ id': ObjectId ('59253478d92fac43dcb5oa') },{' $ set': {'name': 'wang Erma 100 '}})

The result is as follows:

Copy codeThe Code is as follows:
{'_ Id': ObjectId ('59253478d92fac43dcb%a'), 'name': 'wang Erma 100', 'province': 'guangdong ', 'age': 30}

Delete data

To delete data, use the remove () method. If the method has conditions, delete the specified conditions. Otherwise, delete all

Delete the user whose name is Wang Erma 33333.

Db. col. remove ({'name': 'wang Erma 33333 '})

Delete all data (use with caution)

db.col.remove()

The above is all the content of this article. I hope it will be helpful for your learning and support for helping customers.