MongoDB: 2. Basic Usage

原創 xiugq 2018-09-12 03:53
 

須安裝 PyMongo

(注: 以下 > 提示符表示 mongo JS 代碼，>>> 爲 Python 代碼)

1. INSERT

使用 insert 插入文檔。
 


> 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() 可插入新文檔，也可以更新(update)一個已有的文檔。下面是用 PyMongo 寫的相同的代碼。

>>> 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 支持多種複雜的查詢方式，能實現大多數 T-SQL 功能，遠不是 Key-Value 之類的 NoSQL DB 所能比擬的。
相關函數操作看上去非常像 .NET/C# Linq Method Syntax。
有關查詢優化和索引的細節請參考後文。

先準備好所需的測試數據。

> 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 }

主要用到的查詢函數式 find() 和 findOne()，前者返回一個迭代器 cursor，後者返回單個文檔。

(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({name:"user1", age:21})
{ "_id" : ObjectId("4c4528a0b55f2224d447e4b0"), "name" : "user1", "age" : 21, "sex" : 1 }

>>> for u in db.users.find({"name":"user1", "age":21}): print u
...
{u'age': 21.0, u'_id': ObjectId('4c4528a0b55f2224d447e4b0'), u'name': u'user1', u'sex': 1.0}

(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 貌似有點問題)。

>>> 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}

比較操作包括：$gt (>)、$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}

對應的操作符有 $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}

還有一些複雜或專用的查詢另文記錄。

3. Update

可直接用類似 T-SQL 條件表達式更新，或用 Save() 更新從數據庫返回到文檔對象。

# 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() 有幾個參數需要注意。

db.collection.update(criteria, objNew, upsert, mult)

criteria: 需要被更新的條件表達式
objNew: 更新表達式
upsert: 如目標記錄不存在，是否插入新文檔。
multi: 是否更新多個文檔。

# 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}})

還有一些針對集合的更新操作另文記錄。

4. Remove

remove() 用於刪除單個或全部文檔，刪除後的文檔無法恢復。

> 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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