mongoDB - 日常操作四

python 使用 mongodb

easy_install pymongo 
# 安装(python2.7+)

import pymongo
connection=pymongo.Connection('localhost',27017) # 创建连接
db = connection.test_database # 切换数据库
collection = db.test_collection # 获取collection
# db和collection都是延时创建的，在添加Document时才真正创建

文档添加, _id自动创建

import datetime
post = {"author": "Mike",
"text": "My first blog post!",
"tags": ["mongodb", "python", "pymongo"],
"date": datetime.datetime.utcnow()}
posts = db.posts
posts.insert(post)
ObjectId('...')

 

批量插入

new_posts = [{"author": "Mike",
"text": "Another post!",
"tags": ["bulk", "insert"],
"date": datetime.datetime(2009, 11, 12, 11, 14)},
{"author": "Eliot",
"title": "MongoDB is fun",
"text": "and pretty easy too!",
"date": datetime.datetime(2009, 11, 10, 10, 45)}]
posts.insert(new_posts)
[ObjectId('...'), ObjectId('...')]

 

获取数据

获取所有collection
db.collection_names() # 相当于SQL的show tables

获取单个文档
posts.find_one()

 

 

数据查询

查询多个文档
for post in posts.find():
post

加条件的查询
posts.find_one({"author": "Mike"})

高级查询
posts.find({"date": {"$lt": "d"}}).sort("author")

 

统计数量

posts.count()

 

加索引

from pymongo import ASCENDING, DESCENDING
posts.create_index([("date", DESCENDING), ("author", ASCENDING)])

 

查看查询语句的性能

posts.find({"date": {"$lt": "d"}}).sort("author").explain()["cursor"]
posts.find({"date": {"$lt": "d"}}).sort("author").explain()["nscanned"]