MongoDB：2. Basic Usage

数据库 2018-05-31 02:31:08 阅读次数: 0
MongoDB：2. Basic Usage

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摘要：须安装PyMongo( Documentation )。 $ sudo easy_install -U pymongo (注: 以下 提示符表示 mongo JS 代码， 为 Python 代码) 1. INSERT 使用 insert 插入文档。 useblog switchedtodbblog u={name: user1 ,age:23} { name : user1 , age :23}
须安装PyMongo(Documentation)。
$ sudo easy_install -U pymongo
(注: 以下 > 提示符表示 mongo JS 代码，>>> 为 Python 代码)
1. INSERT
使用 insert 插入文档。
> use blog 
switched to db blog 

> u = { name:"user1", age:23 } 
{ "name" : "user1", "age" : 23 } 

> db.users.insert(u) 

> u2 = db.users.findOne({name:"user1"}) 
{ 
        "_id" : ObjectId("4c44fe0edef8f3492fe67d60"), 
        "name" : "user1", 
        "age" : 23 
} 

> u2.age += 3 
26 

> db.users.save(u2) 

> db.users.find() 
{ "_id" : ObjectId("4c44fe0edef8f3492fe67d60"), "name" : "user1", "age" : 26 }
save() 可插入新文档，也可以更新(update)一个已有的文档。下面是用 PyMongo 写的相同的代码。
>>> import pymongo 
>>> conn = pymongo.Connection(host="192.168.1.202") 
>>> db = conn.blog 

>>> u = {"name":"user1", "age":23} 

>>> db.users.save(u) 
ObjectId('4c456e0a499b14047e000000') 

>>> u2 = db.users.find_one({"name":"user1"}) 

>>> u2 
{u'age': 23, u'_id': ObjectId('4c456e0a499b14047e000000'), u'name': u'user1'} 

>>> u2["age"] += 3

>>> db.users.save(u2) 
ObjectId('4c456e0a499b14047e000000') 

>>> for u in db.users.find(): print u 
... 
{u'age': 26, u'_id': ObjectId('4c456e0a499b14047e000000'), u'name': u'user1'}
2. Query
MongoDB 支持多种复杂的查询方式，能实现大多数 T-SQL 功能，远不是 Key-Value 之类的 NoSQL DB 所能比拟的。
相关函数操作看上去非常像 .NET/C# Linq Method Syntax。
有关查询优化和索引的细节请参考后文。
先准备好所需的测试数据。
> use blog 
switched to db blog 

> for (var i = 0; i < 16; i++) db.users.insert({name:"user" + i, age:20 + i, sex:i % 2}) 

> db.users.find() 
{ "_id" : ObjectId("4c452c343d48c8f284b388df"), "name" : "user0", "age" : 20, "sex" : 0 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388e0"), "name" : "user1", "age" : 21, "sex" : 1 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388e1"), "name" : "user2", "age" : 22, "sex" : 0 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388e2"), "name" : "user3", "age" : 23, "sex" : 1 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388e3"), "name" : "user4", "age" : 24, "sex" : 0 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388e4"), "name" : "user5", "age" : 25, "sex" : 1 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388e5"), "name" : "user6", "age" : 26, "sex" : 0 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388e6"), "name" : "user7", "age" : 27, "sex" : 1 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388e7"), "name" : "user8", "age" : 28, "sex" : 0 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388e8"), "name" : "user9", "age" : 29, "sex" : 1 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388e9"), "name" : "user10", "age" : 30, "sex" : 0 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388ea"), "name" : "user11", "age" : 31, "sex" : 1 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388eb"), "name" : "user12", "age" : 32, "sex" : 0 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388ec"), "name" : "user13", "age" : 33, "sex" : 1 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388ed"), "name" : "user14", "age" : 34, "sex" : 0 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388ee"), "name" : "user15", "age" : 35, "sex" : 1 }
主要用到的查询函数式 find() 和 findOne()，前者返回一个迭代器 cursor，后者返回单个文档。
(1) WHERE
# select * from users where name = 'user1'
> db.users.find({name:"user1"}) 
{ "_id" : ObjectId("4c4528a0b55f2224d447e4b0"), "name" : "user1", "age" : 21, "sex" : 1 }
>>> for u in db.users.find({"name":"user1"}): print u 
... 
{u'age': 21.0, u'_id': ObjectId('4c4528a0b55f2224d447e4b0'), u'name': u'user1', u'sex': 1.0}
# select * from users where name = 'user1' and age = 21
> db.users.find({age:21}, {'name':1, 'age':1}) 
{ "_id" : ObjectId("4c452c343d48c8f284b388e0"), "name" : "user1", "age" : 21 }
>>> for u in db.users.find({"age":21}, ["name", "age"]): print u 
... 
{u'age': 21.0, u'_id': ObjectId('4c452c343d48c8f284b388e0'), u'name': u'user1'}
(2) FIELDS
# select name, age from users where age = 21
> db.users.find({age:21}, {'name':1, 'age':1}) 
{ "_id" : ObjectId("4c452c343d48c8f284b388e0"), "name" : "user1", "age" : 21 }
>>> for u in db.users.find({"age":21}, ["name", "age"]): print u 
... 
{u'age': 21.0, u'_id': ObjectId('4c452c343d48c8f284b388e0'), u'name': u'user1'}
# select name, age from users
> db.users.find({}, {'name':1, 'age':1}) 
{ "_id" : ObjectId("4c452c343d48c8f284b388df"), "name" : "user0", "age" : 20 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388e0"), "name" : "user1", "age" : 21 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388e1"), "name" : "user2", "age" : 22 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388e2"), "name" : "user3", "age" : 23 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388e3"), "name" : "user4", "age" : 24 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388e4"), "name" : "user5", "age" : 25 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388e5"), "name" : "user6", "age" : 26 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388e6"), "name" : "user7", "age" : 27 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388e7"), "name" : "user8", "age" : 28 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388e8"), "name" : "user9", "age" : 29 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388e9"), "name" : "user10", "age" : 30 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388ea"), "name" : "user11", "age" : 31 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388eb"), "name" : "user12", "age" : 32 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388ec"), "name" : "user13", "age" : 33 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388ed"), "name" : "user14", "age" : 34 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388ee"), "name" : "user15", "age" : 35 }
>>> for u in db.users.find(fields = ["name", "age"]): print u 
... 
{u'age': 20.0, u'_id': ObjectId('4c452c343d48c8f284b388df'), u'name': u'user0'} 
{u'age': 21.0, u'_id': ObjectId('4c452c343d48c8f284b388e0'), u'name': u'user1'} 
{u'age': 22.0, u'_id': ObjectId('4c452c343d48c8f284b388e1'), u'name': u'user2'} 
{u'age': 23.0, u'_id': ObjectId('4c452c343d48c8f284b388e2'), u'name': u'user3'} 
{u'age': 24.0, u'_id': ObjectId('4c452c343d48c8f284b388e3'), u'name': u'user4'} 
{u'age': 25.0, u'_id': ObjectId('4c452c343d48c8f284b388e4'), u'name': u'user5'} 
{u'age': 26.0, u'_id': ObjectId('4c452c343d48c8f284b388e5'), u'name': u'user6'} 
{u'age': 27.0, u'_id': ObjectId('4c452c343d48c8f284b388e6'), u'name': u'user7'} 
{u'age': 28.0, u'_id': ObjectId('4c452c343d48c8f284b388e7'), u'name': u'user8'} 
{u'age': 29.0, u'_id': ObjectId('4c452c343d48c8f284b388e8'), u'name': u'user9'} 
{u'age': 30.0, u'_id': ObjectId('4c452c343d48c8f284b388e9'), u'name': u'user10'} 
{u'age': 31.0, u'_id': ObjectId('4c452c343d48c8f284b388ea'), u'name': u'user11'} 
{u'age': 32.0, u'_id': ObjectId('4c452c343d48c8f284b388eb'), u'name': u'user12'} 
{u'age': 33.0, u'_id': ObjectId('4c452c343d48c8f284b388ec'), u'name': u'user13'} 
{u'age': 34.0, u'_id': ObjectId('4c452c343d48c8f284b388ed'), u'name': u'user14'} 
{u'age': 35.0, u'_id': ObjectId('4c452c343d48c8f284b388ee'), u'name': u'user15'}
(3) SORT
# select * from users order by age
> db.users.find().sort({age:1}) 
{ "_id" : ObjectId("4c452c343d48c8f284b388df"), "name" : "user0", "age" : 20, "sex" : 0 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388e0"), "name" : "user1", "age" : 21, "sex" : 1 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388e1"), "name" : "user2", "age" : 22, "sex" : 0 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388e2"), "name" : "user3", "age" : 23, "sex" : 1 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388e3"), "name" : "user4", "age" : 24, "sex" : 0 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388e4"), "name" : "user5", "age" : 25, "sex" : 1 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388e5"), "name" : "user6", "age" : 26, "sex" : 0 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388e6"), "name" : "user7", "age" : 27, "sex" : 1 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388e7"), "name" : "user8", "age" : 28, "sex" : 0 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388e8"), "name" : "user9", "age" : 29, "sex" : 1 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388e9"), "name" : "user10", "age" : 30, "sex" : 0 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388ea"), "name" : "user11", "age" : 31, "sex" : 1 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388eb"), "name" : "user12", "age" : 32, "sex" : 0 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388ec"), "name" : "user13", "age" : 33, "sex" : 1 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388ed"), "name" : "user14", "age" : 34, "sex" : 0 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388ee"), "name" : "user15", "age" : 35, "sex" : 1 } 

> db.users.find().sort({age:-1}) 
{ "_id" : ObjectId("4c452c343d48c8f284b388ee"), "name" : "user15", "age" : 35, "sex" : 1 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388ed"), "name" : "user14", "age" : 34, "sex" : 0 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388ec"), "name" : "user13", "age" : 33, "sex" : 1 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388eb"), "name" : "user12", "age" : 32, "sex" : 0 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388ea"), "name" : "user11", "age" : 31, "sex" : 1 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388e9"), "name" : "user10", "age" : 30, "sex" : 0 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388e8"), "name" : "user9", "age" : 29, "sex" : 1 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388e7"), "name" : "user8", "age" : 28, "sex" : 0 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388e6"), "name" : "user7", "age" : 27, "sex" : 1 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388e5"), "name" : "user6", "age" : 26, "sex" : 0 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388e4"), "name" : "user5", "age" : 25, "sex" : 1 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388e3"), "name" : "user4", "age" : 24, "sex" : 0 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388e2"), "name" : "user3", "age" : 23, "sex" : 1 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388e1"), "name" : "user2", "age" : 22, "sex" : 0 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388e0"), "name" : "user1", "age" : 21, "sex" : 1 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388df"), "name" : "user0", "age" : 20, "sex" : 0 }
>>> for u in db.users.find().sort([("age", ASCENDING)]): print u 
... 
{u'age': 20.0, u'_id': ObjectId('4c452c343d48c8f284b388df'), u'name': u'user0', u'sex': 0.0} 
{u'age': 21.0, u'_id': ObjectId('4c452c343d48c8f284b388e0'), u'name': u'user1', u'sex': 1.0} 
{u'age': 22.0, u'_id': ObjectId('4c452c343d48c8f284b388e1'), u'name': u'user2', u'sex': 0.0} 
{u'age': 23.0, u'_id': ObjectId('4c452c343d48c8f284b388e2'), u'name': u'user3', u'sex': 1.0} 
{u'age': 24.0, u'_id': ObjectId('4c452c343d48c8f284b388e3'), u'name': u'user4', u'sex': 0.0} 
{u'age': 25.0, u'_id': ObjectId('4c452c343d48c8f284b388e4'), u'name': u'user5', u'sex': 1.0} 
{u'age': 26.0, u'_id': ObjectId('4c452c343d48c8f284b388e5'), u'name': u'user6', u'sex': 0.0} 
{u'age': 27.0, u'_id': ObjectId('4c452c343d48c8f284b388e6'), u'name': u'user7', u'sex': 1.0} 
{u'age': 28.0, u'_id': ObjectId('4c452c343d48c8f284b388e7'), u'name': u'user8', u'sex': 0.0} 
{u'age': 29.0, u'_id': ObjectId('4c452c343d48c8f284b388e8'), u'name': u'user9', u'sex': 1.0} 
{u'age': 30.0, u'_id': ObjectId('4c452c343d48c8f284b388e9'), u'name': u'user10', u'sex': 0.0} 
{u'age': 31.0, u'_id': ObjectId('4c452c343d48c8f284b388ea'), u'name': u'user11', u'sex': 1.0} 
{u'age': 32.0, u'_id': ObjectId('4c452c343d48c8f284b388eb'), u'name': u'user12', u'sex': 0.0} 
{u'age': 33.0, u'_id': ObjectId('4c452c343d48c8f284b388ec'), u'name': u'user13', u'sex': 1.0} 
{u'age': 34.0, u'_id': ObjectId('4c452c343d48c8f284b388ed'), u'name': u'user14', u'sex': 0.0} 
{u'age': 35.0, u'_id': ObjectId('4c452c343d48c8f284b388ee'), u'name': u'user15', u'sex': 1.0} 

>>> for u in db.users.find().sort([("age", DESCENDING)]): print u 
... 
{u'age': 35.0, u'_id': ObjectId('4c452c343d48c8f284b388ee'), u'name': u'user15', u'sex': 1.0} 
{u'age': 34.0, u'_id': ObjectId('4c452c343d48c8f284b388ed'), u'name': u'user14', u'sex': 0.0} 
{u'age': 33.0, u'_id': ObjectId('4c452c343d48c8f284b388ec'), u'name': u'user13', u'sex': 1.0} 
{u'age': 32.0, u'_id': ObjectId('4c452c343d48c8f284b388eb'), u'name': u'user12', u'sex': 0.0} 
{u'age': 31.0, u'_id': ObjectId('4c452c343d48c8f284b388ea'), u'name': u'user11', u'sex': 1.0} 
{u'age': 30.0, u'_id': ObjectId('4c452c343d48c8f284b388e9'), u'name': u'user10', u'sex': 0.0} 
{u'age': 29.0, u'_id': ObjectId('4c452c343d48c8f284b388e8'), u'name': u'user9', u'sex': 1.0} 
{u'age': 28.0, u'_id': ObjectId('4c452c343d48c8f284b388e7'), u'name': u'user8', u'sex': 0.0} 
{u'age': 27.0, u'_id': ObjectId('4c452c343d48c8f284b388e6'), u'name': u'user7', u'sex': 1.0} 
{u'age': 26.0, u'_id': ObjectId('4c452c343d48c8f284b388e5'), u'name': u'user6', u'sex': 0.0} 
{u'age': 25.0, u'_id': ObjectId('4c452c343d48c8f284b388e4'), u'name': u'user5', u'sex': 1.0} 
{u'age': 24.0, u'_id': ObjectId('4c452c343d48c8f284b388e3'), u'name': u'user4', u'sex': 0.0} 
{u'age': 23.0, u'_id': ObjectId('4c452c343d48c8f284b388e2'), u'name': u'user3', u'sex': 1.0} 
{u'age': 22.0, u'_id': ObjectId('4c452c343d48c8f284b388e1'), u'name': u'user2', u'sex': 0.0} 
{u'age': 21.0, u'_id': ObjectId('4c452c343d48c8f284b388e0'), u'name': u'user1', u'sex': 1.0} 
{u'age': 20.0, u'_id': ObjectId('4c452c343d48c8f284b388df'), u'name': u'user0', u'sex': 0.0}
# select * from users order by sex asce, age desc
> db.users.find().sort({sex:1, age:-1}) 
{ "_id" : ObjectId("4c452c343d48c8f284b388ed"), "name" : "user14", "age" : 34, "sex" : 0 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388eb"), "name" : "user12", "age" : 32, "sex" : 0 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388e9"), "name" : "user10", "age" : 30, "sex" : 0 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388e7"), "name" : "user8", "age" : 28, "sex" : 0 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388e5"), "name" : "user6", "age" : 26, "sex" : 0 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388e3"), "name" : "user4", "age" : 24, "sex" : 0 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388e1"), "name" : "user2", "age" : 22, "sex" : 0 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388df"), "name" : "user0", "age" : 20, "sex" : 0 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388ee"), "name" : "user15", "age" : 35, "sex" : 1 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388ec"), "name" : "user13", "age" : 33, "sex" : 1 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388ea"), "name" : "user11", "age" : 31, "sex" : 1 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388e8"), "name" : "user9", "age" : 29, "sex" : 1 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388e6"), "name" : "user7", "age" : 27, "sex" : 1 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388e4"), "name" : "user5", "age" : 25, "sex" : 1 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388e2"), "name" : "user3", "age" : 23, "sex" : 1 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388e0"), "name" : "user1", "age" : 21, "sex" : 1 }
>>> for u in db.users.find().sort([("sex", ASCENDING), ("age", DESCENDING)]): print u 

... 
{u'age': 34.0, u'_id': ObjectId('4c452c343d48c8f284b388ed'), u'name': u'user14', u'sex': 0.0} 
{u'age': 32.0, u'_id': ObjectId('4c452c343d48c8f284b388eb'), u'name': u'user12', u'sex': 0.0} 
{u'age': 30.0, u'_id': ObjectId('4c452c343d48c8f284b388e9'), u'name': u'user10', u'sex': 0.0} 
{u'age': 28.0, u'_id': ObjectId('4c452c343d48c8f284b388e7'), u'name': u'user8', u'sex': 0.0} 
{u'age': 26.0, u'_id': ObjectId('4c452c343d48c8f284b388e5'), u'name': u'user6', u'sex': 0.0} 
{u'age': 24.0, u'_id': ObjectId('4c452c343d48c8f284b388e3'), u'name': u'user4', u'sex': 0.0} 
{u'age': 22.0, u'_id': ObjectId('4c452c343d48c8f284b388e1'), u'name': u'user2', u'sex': 0.0} 
{u'age': 20.0, u'_id': ObjectId('4c452c343d48c8f284b388df'), u'name': u'user0', u'sex': 0.0} 
{u'age': 35.0, u'_id': ObjectId('4c452c343d48c8f284b388ee'), u'name': u'user15', u'sex': 1.0} 
{u'age': 33.0, u'_id': ObjectId('4c452c343d48c8f284b388ec'), u'name': u'user13', u'sex': 1.0} 
{u'age': 31.0, u'_id': ObjectId('4c452c343d48c8f284b388ea'), u'name': u'user11', u'sex': 1.0} 
{u'age': 29.0, u'_id': ObjectId('4c452c343d48c8f284b388e8'), u'name': u'user9', u'sex': 1.0} 
{u'age': 27.0, u'_id': ObjectId('4c452c343d48c8f284b388e6'), u'name': u'user7', u'sex': 1.0} 
{u'age': 25.0, u'_id': ObjectId('4c452c343d48c8f284b388e4'), u'name': u'user5', u'sex': 1.0} 
{u'age': 23.0, u'_id': ObjectId('4c452c343d48c8f284b388e2'), u'name': u'user3', u'sex': 1.0} 
{u'age': 21.0, u'_id': ObjectId('4c452c343d48c8f284b388e0'), u'name': u'user1', u'sex': 1.0} 

>>> for u in db.users.find(sort = [("sex", ASCENDING), ("age", DESCENDING)]): print u 
... 
{u'age': 34.0, u'_id': ObjectId('4c452c343d48c8f284b388ed'), u'name': u'user14', u'sex': 0.0} 
{u'age': 32.0, u'_id': ObjectId('4c452c343d48c8f284b388eb'), u'name': u'user12', u'sex': 0.0} 
{u'age': 30.0, u'_id': ObjectId('4c452c343d48c8f284b388e9'), u'name': u'user10', u'sex': 0.0} 
{u'age': 28.0, u'_id': ObjectId('4c452c343d48c8f284b388e7'), u'name': u'user8', u'sex': 0.0} 
{u'age': 26.0, u'_id': ObjectId('4c452c343d48c8f284b388e5'), u'name': u'user6', u'sex': 0.0} 
{u'age': 24.0, u'_id': ObjectId('4c452c343d48c8f284b388e3'), u'name': u'user4', u'sex': 0.0} 
{u'age': 22.0, u'_id': ObjectId('4c452c343d48c8f284b388e1'), u'name': u'user2', u'sex': 0.0} 
{u'age': 20.0, u'_id': ObjectId('4c452c343d48c8f284b388df'), u'name': u'user0', u'sex': 0.0} 
{u'age': 35.0, u'_id': ObjectId('4c452c343d48c8f284b388ee'), u'name': u'user15', u'sex': 1.0} 
{u'age': 33.0, u'_id': ObjectId('4c452c343d48c8f284b388ec'), u'name': u'user13', u'sex': 1.0} 
{u'age': 31.0, u'_id': ObjectId('4c452c343d48c8f284b388ea'), u'name': u'user11', u'sex': 1.0} 
{u'age': 29.0, u'_id': ObjectId('4c452c343d48c8f284b388e8'), u'name': u'user9', u'sex': 1.0} 
{u'age': 27.0, u'_id': ObjectId('4c452c343d48c8f284b388e6'), u'name': u'user7', u'sex': 1.0} 
{u'age': 25.0, u'_id': ObjectId('4c452c343d48c8f284b388e4'), u'name': u'user5', u'sex': 1.0} 
{u'age': 23.0, u'_id': ObjectId('4c452c343d48c8f284b388e2'), u'name': u'user3', u'sex': 1.0} 
{u'age': 21.0, u'_id': ObjectId('4c452c343d48c8f284b388e0'), u'name': u'user1', u'sex': 1.0}
(4) SLICE
# select * from users skip 2 limit 3
> db.users.find().skip(2).limit(3) 
{ "_id" : ObjectId("4c452c343d48c8f284b388e1"), "name" : "user2", "age" : 22, "sex" : 0 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388e2"), "name" : "user3", "age" : 23, "sex" : 1 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388e3"), "name" : "user4", "age" : 24, "sex" : 0 }
>>> for u in db.users.find().skip(2).limit(3): print u 
... 
{u'age': 22.0, u'_id': ObjectId('4c452c343d48c8f284b388e1'), u'name': u'user2', u'sex': 0.0} 
{u'age': 23.0, u'_id': ObjectId('4c452c343d48c8f284b388e2'), u'name': u'user3', u'sex': 1.0} 
{u'age': 24.0, u'_id': ObjectId('4c452c343d48c8f284b388e3'), u'name': u'user4', u'sex': 0.0} 

>>> for u in db.users.find(skip = 2, limit = 3): print u 
... 
{u'age': 22.0, u'_id': ObjectId('4c452c343d48c8f284b388e1'), u'name': u'user2', u'sex': 0.0} 
{u'age': 23.0, u'_id': ObjectId('4c452c343d48c8f284b388e2'), u'name': u'user3', u'sex': 1.0} 
{u'age': 24.0, u'_id': ObjectId('4c452c343d48c8f284b388e3'), u'name': u'user4', u'sex': 0.0}
可以用切片代替 skip & limit (mongo 中的 $slice 貌似有点问题)。
>>> for u in db.users.find()[2:5]: print u 
... 
{u'age': 22.0, u'_id': ObjectId('4c452c343d48c8f284b388e1'), u'name': u'user2', u'sex': 0.0} 
{u'age': 23.0, u'_id': ObjectId('4c452c343d48c8f284b388e2'), u'name': u'user3', u'sex': 1.0} 
{u'age': 24.0, u'_id': ObjectId('4c452c343d48c8f284b388e3'), u'name': u'user4', u'sex': 0.0}
(5) Conditional Operators
# select * from users where sex = 1 and age > 23 and age < 28
> db.users.find({sex:1, age:{$gt:23, $lt:28}}) 
{ "_id" : ObjectId("4c452c343d48c8f284b388e4"), "name" : "user5", "age" : 25, "sex" : 1 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388e6"), "name" : "user7", "age" : 27, "sex" : 1 }
>>> for u in db.users.find({"sex":1, "age":{"$gt":23, "$lt":28}}): print u 
... 
{u'age': 25.0, u'_id': ObjectId('4c452c343d48c8f284b388e4'), u'name': u'user5', u'sex': 1.0} 
{u'age': 27.0, u'_id': ObjectId('4c452c343d48c8f284b388e6'), u'name': u'user7', u'sex': 1.0}
比较操作包括：$gt (>)、$lt (<)、$gte (>=)、$lte(<=)、$ne (!=)。
(6) IN
# select * from users where age in (23, 26, 32)
> db.users.find({age:{$in:[23,26,32]}}) 
{ "_id" : ObjectId("4c452c343d48c8f284b388e2"), "name" : "user3", "age" : 23, "sex" : 1 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388e5"), "name" : "user6", "age" : 26, "sex" : 0 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388eb"), "name" : "user12", "age" : 32, "sex" : 0 }
>>> for u in db.users.find({"age":{"$in":(23, 26, 32)}}): print u 
... 
{u'age': 23.0, u'_id': ObjectId('4c452c343d48c8f284b388e2'), u'name': u'user3', u'sex': 1.0} 
{u'age': 26.0, u'_id': ObjectId('4c452c343d48c8f284b388e5'), u'name': u'user6', u'sex': 0.0} 
{u'age': 32.0, u'_id': ObjectId('4c452c343d48c8f284b388eb'), u'name': u'user12', u'sex': 0.0}
对应的操作符有 $nin (not in)。
(7) COUNT
# select count(*) from users where age > 30
> db.users.find({age:{$gt:30}}).count() 
5
>>> db.users.find({"age":{"$gt":30}}).count() 
5
(8) OR
# select * from users where age = 25 or age = 28
# select * from users where age <= 23 or age >= 33
> db.users.find({$or:[{age:25}, {age:28}]}) 
{ "_id" : ObjectId("4c452c343d48c8f284b388e4"), "name" : "user5", "age" : 25, "sex" : 1 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388e7"), "name" : "user8", "age" : 28, "sex" : 0 } 

> db.users.find({$or:[{age:{$lte:23}}, {age:{$gte:33}}]}) 
{ "_id" : ObjectId("4c452c343d48c8f284b388df"), "name" : "user0", "age" : 20, "sex" : 0 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388e0"), "name" : "user1", "age" : 21, "sex" : 1 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388e1"), "name" : "user2", "age" : 22, "sex" : 0 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388e2"), "name" : "user3", "age" : 23, "sex" : 1 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388ec"), "name" : "user13", "age" : 33, "sex" : 1 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388ed"), "name" : "user14", "age" : 34, "sex" : 0 } 
{ "_id" : ObjectId("4c452c343d48c8f284b388ee"), "name" : "user15", "age" : 35, "sex" : 1 }
>>> for u in db.users.find({"$or":[{"age":25}, {"age":28}]}): print u 
... 
{u'age': 25.0, u'_id': ObjectId('4c452c343d48c8f284b388e4'), u'name': u'user5', u'sex': 1.0} 
{u'age': 28.0, u'_id': ObjectId('4c452c343d48c8f284b388e7'), u'name': u'user8', u'sex': 0.0} 

>>> for u in db.users.find({"$or":[{"age":{"$lte":23}}, {"age":{"$gte":33}}]}): print u 
... 
{u'age': 20.0, u'_id': ObjectId('4c452c343d48c8f284b388df'), u'name': u'user0', u'sex': 0.0} 
{u'age': 21.0, u'_id': ObjectId('4c452c343d48c8f284b388e0'), u'name': u'user1', u'sex': 1.0} 
{u'age': 22.0, u'_id': ObjectId('4c452c343d48c8f284b388e1'), u'name': u'user2', u'sex': 0.0} 
{u'age': 23.0, u'_id': ObjectId('4c452c343d48c8f284b388e2'), u'name': u'user3', u'sex': 1.0} 
{u'age': 33.0, u'_id': ObjectId('4c452c343d48c8f284b388ec'), u'name': u'user13', u'sex': 1.0} 
{u'age': 34.0, u'_id': ObjectId('4c452c343d48c8f284b388ed'), u'name': u'user14', u'sex': 0.0} 
{u'age': 35.0, u'_id': ObjectId('4c452c343d48c8f284b388ee'), u'name': u'user15', u'sex': 1.0}
还有一些复杂或专用的查询另文记录。
3. Update
可直接用类似 T-SQL 条件表达式更新，或用 Save() 更新从数据库返回到文档对象。
# update users set age = 100, sex = 0 where name = 'user1'
> db.users.update({name:"user1"}, {$set:{age:100, sex:0}})
>>> db.users.update({"name":"user1"}, {"$set":{"age":100, "sex":0}})
update() 有几个参数需要注意。
db.collection.update(criteria, objNew, upsert, mult)
criteria: 需要被更新的条件表达式
objNew: 更新表达式
upsert: 如目标记录不存在，是否插入新文档。
multi: 是否更新多个文档。
# update users set age = age + 10
> db.users.update({}, {$inc:{age:10}}, false, true)
>>> db.users.update({}, {"$inc":{"age":10}}, multi=True)
# update users set age = age + 10, sex = 1 where name = 'user1'
> db.users.update({name:"user1"}, {$inc:{age:10}, $set:{sex:1}}) >>> db.users.update({"name":"user1"}, {"$inc":{"age":10}, "$set":{"sex":1}})
还有一些针对集合的更新操作另文记录。
4. Remove
remove() 用于删除单个或全部文档，删除后的文档无法恢复。
> use blog 
switched to db blog 

> for (var i = 0; i < 10; i++) db.users.insert({name : "user" + i, age : 20 + i}) 

> db.users.find() 
{ "_id" : ObjectId("4c4508818c4a1e0bf570460d"), "name" : "user0", "age" : 20 } 
{ "_id" : ObjectId("4c4508818c4a1e0bf570460e"), "name" : "user1", "age" : 21 } 
{ "_id" : ObjectId("4c4508818c4a1e0bf570460f"), "name" : "user2", "age" : 22 } 
{ "_id" : ObjectId("4c4508818c4a1e0bf5704610"), "name" : "user3", "age" : 23 } 
{ "_id" : ObjectId("4c4508818c4a1e0bf5704611"), "name" : "user4", "age" : 24 } 
{ "_id" : ObjectId("4c4508818c4a1e0bf5704612"), "name" : "user5", "age" : 25 } 
{ "_id" : ObjectId("4c4508818c4a1e0bf5704613"), "name" : "user6", "age" : 26 } 
{ "_id" : ObjectId("4c4508818c4a1e0bf5704614"), "name" : "user7", "age" : 27 } 
{ "_id" : ObjectId("4c4508818c4a1e0bf5704615"), "name" : "user8", "age" : 28 } 
{ "_id" : ObjectId("4c4508818c4a1e0bf5704616"), "name" : "user9", "age" : 29 } 

> id = db.users.findOne({name:"user2"})._id 
ObjectId("4c4508818c4a1e0bf570460f") 

> db.users.remove(id) 

> db.users.find() 
{ "_id" : ObjectId("4c4508818c4a1e0bf570460d"), "name" : "user0", "age" : 20 } 
{ "_id" : ObjectId("4c4508818c4a1e0bf570460e"), "name" : "user1", "age" : 21 } 
{ "_id" : ObjectId("4c4508818c4a1e0bf5704610"), "name" : "user3", "age" : 23 } 
{ "_id" : ObjectId("4c4508818c4a1e0bf5704611"), "name" : "user4", "age" : 24 } 
{ "_id" : ObjectId("4c4508818c4a1e0bf5704612"), "name" : "user5", "age" : 25 } 
{ "_id" : ObjectId("4c4508818c4a1e0bf5704613"), "name" : "user6", "age" : 26 } 
{ "_id" : ObjectId("4c4508818c4a1e0bf5704614"), "name" : "user7", "age" : 27 } 
{ "_id" : ObjectId("4c4508818c4a1e0bf5704615"), "name" : "user8", "age" : 28 } 
{ "_id" : ObjectId("4c4508818c4a1e0bf5704616"), "name" : "user9", "age" : 29 } 

> db.users.remove() 

> db.users.find()
Python:
>>> for i in range(10): db.users.insert({"name":"user"+str(i), "age":20+i}) 
... 
ObjectId('4c456e8b499b14047e000001') 
ObjectId('4c456e8b499b14047e000002') 
ObjectId('4c456e8b499b14047e000003') 
ObjectId('4c456e8b499b14047e000004') 
ObjectId('4c456e8b499b14047e000005') 
ObjectId('4c456e8b499b14047e000006') 
ObjectId('4c456e8b499b14047e000007') 
ObjectId('4c456e8b499b14047e000008') 
ObjectId('4c456e8b499b14047e000009') 
ObjectId('4c456e8b499b14047e00000a') 

>>> id = db.users.find_one({"name":"user2"})["_id"] 

>>> id 
ObjectId('4c456e8b499b14047e000003') 

>>> db.users.remove(id) 

>>> for u in db.users.find(): print u 
... 
{u'age': 20, u'_id': ObjectId('4c456e8b499b14047e000001'), u'name': u'user0'} 
{u'age': 21, u'_id': ObjectId('4c456e8b499b14047e000002'), u'name': u'user1'} 
{u'age': 23, u'_id': ObjectId('4c456e8b499b14047e000004'), u'name': u'user3'} 
{u'age': 24, u'_id': ObjectId('4c456e8b499b14047e000005'), u'name': u'user4'} 
{u'age': 25, u'_id': ObjectId('4c456e8b499b14047e000006'), u'name': u'user5'} 
{u'age': 26, u'_id': ObjectId('4c456e8b499b14047e000007'), u'name': u'user6'} 
{u'age': 27, u'_id': ObjectId('4c456e8b499b14047e000008'), u'name': u'user7'} 
{u'age': 28, u'_id': ObjectId('4c456e8b499b14047e000009'), u'name': u'user8'} 
{u'age': 29, u'_id': ObjectId('4c456e8b499b14047e00000a'), u'name': u'user9'} 

>>> db.users.remove() 

>>> for u in db.users.find(): print u 
... 
>>>

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