建立基本连接

首先我们需要建立一个连接,连接 MongoDB 时,我们需要使用 PyMongo 库中的 MongoClient 来建立连接,默认连接的地址是 mongodb://localhost:27017

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from pymongo import MongoClient

clinet = MongoClient("mongodb://localhost:27017")
db = clinet["demo"]
col = db["demo"]

首先通过上面的代码创建 数据库对象和集合对象。

  • 数据库连接实例 MongoClient
  • 数据库实例 demo
  • 集合实例 demo

基本命令

查看数据库信息

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server_info = clinet.server_info()

输出信息:

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{
"version":"4.2.6",
"gitVersion":"20364840b8f1af16917e4c23c1b5f5efd8b352f8",
"modules":[

],
"allocator":"tcmalloc",
"javascriptEngine":"mozjs",
"sysInfo":"deprecated",
"versionArray":[
4,
2,
6,
0
],
"openssl":{
"running":"OpenSSL 1.1.1 11 Sep 2018",
"compiled":"OpenSSL 1.1.1 11 Sep 2018"
},
"buildEnvironment":{
"distmod":"ubuntu1804",
"distarch":"x86_64",
"cc":"/opt/mongodbtoolchain/v3/bin/gcc: gcc (GCC) 8.2.0",
"ccflags":"-fno-omit-frame-pointer -fno-strict-aliasing -ggdb -pthread -Wall -Wsign-compare -Wno-unknown-pragmas -Winvalid-pch -Werror -O2 -Wno-unused-local-typedefs -Wno-unused-function -Wno-deprecated-declarations -Wno-unused-const-variable -Wno-unused-but-set-variable -Wno-missing-braces -fstack-protector-strong -fno-builtin-memcmp",
"cxx":"/opt/mongodbtoolchain/v3/bin/g++: g++ (GCC) 8.2.0",
"cxxflags":"-Woverloaded-virtual -Wno-maybe-uninitialized -fsized-deallocation -std=c++17",
"linkflags":"-pthread -Wl,-z,now -rdynamic -Wl,--fatal-warnings -fstack-protector-strong -fuse-ld=gold -Wl,--build-id -Wl,--hash-style=gnu -Wl,-z,noexecstack -Wl,--warn-execstack -Wl,-z,relro",
"target_arch":"x86_64",
"target_os":"linux"
},
"bits":64,
"debug":false,
"maxBsonObjectSize":16777216,
"storageEngines":[
"biggie",
"devnull",
"ephemeralForTest",
"wiredTiger"
],
"ok":1
}

显示当前数据库服务器上的数据库名

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database_names = clinet.list_database_names()

输出信息:

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['admin', 'config', 'demo', 'local']

如果没有 demo 数据库是因为在没有插入数据的情况下是不会被创建的,只有第一次插入数据,会自动的创建数据库以及对应的集合。

显示当前数据库上的全部集合名

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collection_names = db.list_collection_names()

输出信息:

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['demo']

插入文档

插入一个文档

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demo = {
"author": "Sitoi",
"age": 22,
"title": "Sitoi-blog",
"tags": ["man", "spider"]
}
demo_id = col.insert_one(demo).inserted_id

输出信息:

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5ee3806bb6c75d29c94aa9fc

插入多个文档

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demos = [
{"author": "blog", "age": 18, "title": "blog", "text": "Sitoi Blog"},
{"author": "bash", "age": 30, "title": "bash", "text": "Sitoi Blog"},
{"author": "python", "age": 50, "title": "language", "text": "Sitoi Blog"},
{"author": "mongodb", "age": 80, "title": "NoSQL", "text": "Sitoi Blog"},
{"author": "pymongo", "age": 97, "title": "Python for MongoDB", "text": "Sitoi Blog"},
]
demo_ids = col.insert_many(demos).inserted_ids

输出信息:

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[ObjectId('5ee3806bb6c75d29c94aa9fd'), ObjectId('5ee3806bb6c75d29c94aa9fe'), ObjectId('5ee3806bb6c75d29c94aa9ff'), ObjectId('5ee3806bb6c75d29c94aaa00'), ObjectId('5ee3806bb6c75d29c94aaa01')]

查询文档

查询单个文档

返回查询的第一条find_one 里面可以填写查询条件

参数说明:

  • filter:查询条件
  • projection:映射条件
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query = {}
projection = None
result = col.find_one(filter=query, projection=projection)

查询结果:

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{'_id': ObjectId('5ee3806bb6c75d29c94aa9fc'), 'author': 'Sitoi', 'age': 22, 'title': 'Sitoi-blog', 'tags': ['man', 'spider']}

查询多个文档

返回一个对象,find 里面可以填写 查询条件

  • filter:查询条件
  • projection:映射条件
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query = {}
projection = None
result = col.find(filter=query, projection=projection)

查询结果:

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<pymongo.cursor.Cursor object at 0x7f695ed56c88>

通过For循环

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results = col.find()
for result in results:
print(result)

遍历结果:

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{'_id': ObjectId('5ee3806bb6c75d29c94aa9fc'), 'author': 'Sitoi', 'age': 22, 'title': 'Sitoi-blog', 'tags': ['man', 'spider']}
{'_id': ObjectId('5ee3806bb6c75d29c94aa9fd'), 'author': 'blog', 'age': 18, 'title': 'blog', 'text': 'Sitoi Blog'}
{'_id': ObjectId('5ee3806bb6c75d29c94aa9fe'), 'author': 'bash', 'age': 30, 'title': 'bash', 'text': 'Sitoi Blog'}
{'_id': ObjectId('5ee3806bb6c75d29c94aa9ff'), 'author': 'python', 'age': 50, 'title': 'language', 'text': 'Sitoi Blog'}
{'_id': ObjectId('5ee3806bb6c75d29c94aaa00'), 'author': 'mongodb', 'age': 80, 'title': 'NoSQL', 'text': 'Sitoi Blog'}
{'_id': ObjectId('5ee3806bb6c75d29c94aaa01'), 'author': 'pymongo', 'age': 97, 'title': 'Python for MongoDB', 'text': 'Sitoi Blog'}

指定返回哪些字段

通过 projection 参数控制返回的结果包含哪些字段

示例一:所有字段

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results = col.find()

查询结果:

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{'_id': ObjectId('5ee3806bb6c75d29c94aa9fc'), 'author': 'Sitoi', 'age': 22, 'title': 'Sitoi-blog', 'tags': ['man', 'spider']}
{'_id': ObjectId('5ee3806bb6c75d29c94aa9fd'), 'author': 'blog', 'age': 18, 'title': 'blog', 'text': 'Sitoi Blog'}
{'_id': ObjectId('5ee3806bb6c75d29c94aa9fe'), 'author': 'bash', 'age': 30, 'title': 'bash', 'text': 'Sitoi Blog'}
{'_id': ObjectId('5ee3806bb6c75d29c94aa9ff'), 'author': 'python', 'age': 50, 'title': 'language', 'text': 'Sitoi Blog'}
{'_id': ObjectId('5ee3806bb6c75d29c94aaa00'), 'author': 'mongodb', 'age': 80, 'title': 'NoSQL', 'text': 'Sitoi Blog'}
{'_id': ObjectId('5ee3806bb6c75d29c94aaa01'), 'author': 'pymongo', 'age': 97, 'title': 'Python for MongoDB', 'text': 'Sitoi Blog'}

示例二:用字典指定要显示的哪几个字段

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query = {}
projection = {"_id": True, "author": True}
results = col.find(filter=query, projection=projection)

查询结果:

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{'_id': ObjectId('5ee3806bb6c75d29c94aa9fc'), 'author': 'Sitoi'}
{'_id': ObjectId('5ee3806bb6c75d29c94aa9fd'), 'author': 'blog'}
{'_id': ObjectId('5ee3806bb6c75d29c94aa9fe'), 'author': 'bash'}
{'_id': ObjectId('5ee3806bb6c75d29c94aa9ff'), 'author': 'python'}
{'_id': ObjectId('5ee3806bb6c75d29c94aaa00'), 'author': 'mongodb'}
{'_id': ObjectId('5ee3806bb6c75d29c94aaa01'), 'author': 'pymongo'}

示例三:用字典指定去掉哪些字段

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query = {}
projection = {"_id": False, "author": False}
results = col.find(query, projection=projection)

查询结果:

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{'age': 22, 'title': 'Sitoi-blog', 'tags': ['man', 'spider']}
{'age': 18, 'title': 'blog', 'text': 'Sitoi Blog'}
{'age': 30, 'title': 'bash', 'text': 'Sitoi Blog'}
{'age': 50, 'title': 'language', 'text': 'Sitoi Blog'}
{'age': 80, 'title': 'NoSQL', 'text': 'Sitoi Blog'}
{'age': 97, 'title': 'Python for MongoDB', 'text': 'Sitoi Blog'}

示例四:用列表指定要显示哪几个字段

_id 不指定为 False 则必定返回

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query = {}
projection = ["author", "title"]
results = col.find(filter=query, projection=projection)

查询结果:

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{'_id': ObjectId('5ee3806bb6c75d29c94aa9fc'), 'author': 'Sitoi', 'title': 'Sitoi-blog'}
{'_id': ObjectId('5ee3806bb6c75d29c94aa9fd'), 'author': 'blog', 'title': 'blog'}
{'_id': ObjectId('5ee3806bb6c75d29c94aa9fe'), 'author': 'bash', 'title': 'bash'}
{'_id': ObjectId('5ee3806bb6c75d29c94aa9ff'), 'author': 'python', 'title': 'language'}
{'_id': ObjectId('5ee3806bb6c75d29c94aaa00'), 'author': 'mongodb', 'title': 'NoSQL'}
{'_id': ObjectId('5ee3806bb6c75d29c94aaa01'), 'author': 'pymongo', 'title': 'Python for MongoDB'}

指定查询条件

符号 含义 示例
$lt 小于 {‘age’: {‘$lt’: 18}}
$gt 大于 {‘age’: {‘$gt’: 18}}
$lte 小于等于 {‘age’: {‘$lte’: 18}}
$gte 大于等于 {‘age’: {‘$gte’: 18}}
$ne 不等于 {‘age’: {‘$ne’: 18}}
$in 在范围内 {‘age’: {‘$in’: [18, 22]}}
$nin 不在范围内 {‘age’: {‘$nin’: [18, 22]}}
$all 条件内所有值 {‘age’: {‘$all’: [18, 22]}}

示例:指定范围,大于等于,小于等于

10 <= 年龄 <= 30

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query = {"age": {"$gte": 10, "$lte": 30}}
projection = None
results = col.find(filter=query, projection=projection)

查询结果:

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{'_id': ObjectId('5ee3806bb6c75d29c94aa9fc'), 'author': 'Sitoi', 'age': 22, 'title': 'Sitoi-blog', 'tags': ['man', 'spider']}
{'_id': ObjectId('5ee3806bb6c75d29c94aa9fd'), 'author': 'blog', 'age': 18, 'title': 'blog', 'text': 'Sitoi Blog'}
{'_id': ObjectId('5ee3806bb6c75d29c94aa9fe'), 'author': 'bash', 'age': 30, 'title': 'bash', 'text': 'Sitoi Blog'}

并列查询

示例一:不同字段,并列条件

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query = {"author": "Sitoi", "age": 22}
projection = None
results = col.find(filter=query, projection=projection)

查询结果:

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{'_id': ObjectId('5ee3806bb6c75d29c94aa9fc'), 'author': 'Sitoi', 'age': 22, 'title': 'Sitoi-blog', 'tags': ['man', 'spider']}

示例二:相同字段,并列条件

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# 错误:
query = {"age": {"$gt": 10}, "age": {"$lt": 20}}
# 正确:
query = {"age": {"$gte": 10, "$lte": 20}}
projection = None
results = col.find(filter=query, projection=projection)

查询结果:

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{'_id': ObjectId('5ee3806bb6c75d29c94aa9fd'), 'author': 'blog', 'age': 18, 'title': 'blog', 'text': 'Sitoi Blog'}

或条件查询

示例一:不同字段,或条件

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query = {"$or": [{"age": 22}, {"author": "blog"}]}
projection = None
results = col.find(filter=query, projection=projection)

查询结果:

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{'_id': ObjectId('5ee3806bb6c75d29c94aa9fc'), 'author': 'Sitoi', 'age': 22, 'title': 'Sitoi-blog', 'tags': ['man', 'spider']}
{'_id': ObjectId('5ee3806bb6c75d29c94aa9fd'), 'author': 'blog', 'age': 18, 'title': 'blog', 'text': 'Sitoi Blog'}

示例二:相同字段,或条件

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query = {"$or": [{"age": 22}, {"age": 18}]}
projection = None
results = col.find(filter=query, projection=projection)

查询结果:

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{'_id': ObjectId('5ee3806bb6c75d29c94aa9fc'), 'author': 'Sitoi', 'age': 22, 'title': 'Sitoi-blog', 'tags': ['man', 'spider']}
{'_id': ObjectId('5ee3806bb6c75d29c94aa9fd'), 'author': 'blog', 'age': 18, 'title': 'blog', 'text': 'Sitoi Blog'}

字段是否存在

示例一:字段不存在

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query = {"text": None}
projection = None
results = col.find(filter=query, projection=projection)

查询结果:

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{'_id': ObjectId('5ee3806bb6c75d29c94aa9fc'), 'author': 'Sitoi', 'age': 22, 'title': 'Sitoi-blog', 'tags': ['man', 'spider']}

示例二:字段存在

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query = {"text": {"$ne": None}}
projection = None
results = col.find(filter=query, projection=projection)

查询结果:

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{'_id': ObjectId('5ee3806bb6c75d29c94aa9fd'), 'author': 'blog', 'age': 18, 'title': 'blog', 'text': 'Sitoi Blog'}
{'_id': ObjectId('5ee3806bb6c75d29c94aa9fe'), 'author': 'bash', 'age': 30, 'title': 'bash', 'text': 'Sitoi Blog'}
{'_id': ObjectId('5ee3806bb6c75d29c94aa9ff'), 'author': 'python', 'age': 50, 'title': 'language', 'text': 'Sitoi Blog'}
{'_id': ObjectId('5ee3806bb6c75d29c94aaa00'), 'author': 'mongodb', 'age': 80, 'title': 'NoSQL', 'text': 'Sitoi Blog'}
{'_id': ObjectId('5ee3806bb6c75d29c94aaa01'), 'author': 'pymongo', 'age': 97, 'title': 'Python for MongoDB', 'text': 'Sitoi Blog'}

正则查询

这里使用 $regex 来指定正则匹配,^S.* 代表以 S 开头的正则表达式。
这里将一些功能符号再归类为下表。

符号 含义 示例 示例含义
$regex 匹配正则表达式 {‘author’: {‘$regex’: ‘^S.*’}} authorS 开头
$exists 属性是否存在 {‘author’: {‘$exists’: True}} author 属性存在
$type 类型判断 {‘age’: {‘$type’: ‘int’}} age 的类型为 int
$mod 数字模操作 {‘age’: {‘$mod’: [5, 0]}} 年龄模 50
$text 文本查询 {‘$text’: {‘$search’: ‘Sitoi’}} text 类型的属性中包含 Sitoi 字符串
$where 高级条件查询 {‘$where’: ‘obj.fans_count == obj.follows_count’} 自身粉丝数等于关注数
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query = {"name": {"$regex": "^M.*"}}
projection = {}
result = col.find(filter=query, projection=projection)

查询结果:

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{'_id': ObjectId('5ee3806bb6c75d29c94aa9fc'), 'author': 'Sitoi', 'age': 22, 'title': 'Sitoi-blog', 'tags': ['man', 'spider']}

计数

根据查询条件计数

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query = {}
count = col.count_documents(filter=query)

文档条数:

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排序

List 嵌套 tuple 的方式即可:[(字段名1排序方式1),(字段名2排序方式2)]

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result = col.find().sort([("author", 1), ("title", 1)])

排序结果:

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{'_id': ObjectId('5ee3806bb6c75d29c94aa9fc'), 'author': 'Sitoi', 'age': 22, 'title': 'Sitoi-blog', 'tags': ['man', 'spider']}
{'_id': ObjectId('5ee3806bb6c75d29c94aa9fe'), 'author': 'bash', 'age': 30, 'title': 'bash', 'text': 'Sitoi Blog'}
{'_id': ObjectId('5ee3806bb6c75d29c94aa9fd'), 'author': 'blog', 'age': 18, 'title': 'blog', 'text': 'Sitoi Blog'}
{'_id': ObjectId('5ee3806bb6c75d29c94aaa00'), 'author': 'mongodb', 'age': 80, 'title': 'NoSQL', 'text': 'Sitoi Blog'}
{'_id': ObjectId('5ee3806bb6c75d29c94aaa01'), 'author': 'pymongo', 'age': 97, 'title': 'Python for MongoDB', 'text': 'Sitoi Blog'}
{'_id': ObjectId('5ee3806bb6c75d29c94aa9ff'), 'author': 'python', 'age': 50, 'title': 'language', 'text': 'Sitoi Blog'}

跳过

跳过一个

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result = col.find().skip(1)

查询结果:

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{'_id': ObjectId('5ee3806bb6c75d29c94aa9fd'), 'author': 'blog', 'age': 18, 'title': 'blog', 'text': 'Sitoi Blog'}
{'_id': ObjectId('5ee3806bb6c75d29c94aa9fe'), 'author': 'bash', 'age': 30, 'title': 'bash', 'text': 'Sitoi Blog'}
{'_id': ObjectId('5ee3806bb6c75d29c94aa9ff'), 'author': 'python', 'age': 50, 'title': 'language', 'text': 'Sitoi Blog'}
{'_id': ObjectId('5ee3806bb6c75d29c94aaa00'), 'author': 'mongodb', 'age': 80, 'title': 'NoSQL', 'text': 'Sitoi Blog'}
{'_id': ObjectId('5ee3806bb6c75d29c94aaa01'), 'author': 'pymongo', 'age': 97, 'title': 'Python for MongoDB', 'text': 'Sitoi Blog'}

限制

限制最多返回多少个

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result = col.find().limit(1)

查询结果:

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{'_id': ObjectId('5ee3806bb6c75d29c94aa9fc'), 'author': 'Sitoi', 'age': 22, 'title': 'Sitoi-blog', 'tags': ['man', 'spider']}

更新文档

更新单个文档

update_one 只更新第一个文档。

参数说明:

  • filter:需要更新的数据的查询条件
  • update:包含更新的方式,以及更新的内容
  • upsert:不存在是否插入,更新的数据
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query = {"age": 18}
update = {"$set": {"age": 20}}
modified_count = col.update_one(filter=query, update=update, upsert=False).modified_count

更新条数:

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1

更新多个文档

使用方法和 update_one 一致

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query = {"text": "Sitoi Blog"}
update = {"$set": {"text": "Sitoi PyMongo"}}
modified_count = col.update_many(filter=query, update=update, upsert=False).modified_count

更新条数:

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删除文档

删除单个文档

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query = {"author": "Sitoi"}
result = col.delete_one(filter=query).deleted_count

删除条数:

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删除多个文档

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query = {}
results = col.delete_many(filter=query).deleted_count

删除条数:

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5

附录(代码)

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from pymongo import MongoClient

clinet = MongoClient("mongodb://localhost:27017")

db = clinet["demo"]
col = db["demo"]

print(">>> 查看数据库信息")
server_info = clinet.server_info()
print(server_info)

print(">>> 显示当前数据库服务器上的数据库名")
database_names = clinet.list_database_names()
print(database_names)

print(">>> 显示当前数据库上的全部集合名")
collection_names = db.list_collection_names()
print(collection_names)

print(">>> 插入一个文档")
demo = {
"author": "Sitoi",
"age": 22,
"title": "Sitoi-blog",
"tags": ["man", "spider"]
}
demo_id = col.insert_one(demo).inserted_id
print(demo_id)

print(">>> 插入多个文档")
demos = [
{"author": "blog", "age": 18, "title": "blog", "text": "Sitoi Blog"},
{"author": "bash", "age": 30, "title": "bash", "text": "Sitoi Blog"},
{"author": "python", "age": 50, "title": "language", "text": "Sitoi Blog"},
{"author": "mongodb", "age": 80, "title": "NoSQL", "text": "Sitoi Blog"},
{"author": "pymongo", "age": 97, "title": "Python for MongoDB", "text": "Sitoi Blog"},
]
demo_ids = col.insert_many(demos).inserted_ids
print(demo_ids)

print(">>> 查询单个文档")
query = {}
projection = None
result = col.find_one(filter=query, projection=projection)
print(result)

print(">>> 查询多个文档")
query = {}
projection = None
result = col.find(filter=query, projection=projection)
for one in result:
print(one)

print(">>> 所有字段")

results = col.find()
for one in results:
print(one)

print(">>> 用字典指定要显示的哪几个字段")
query = {}
projection = {"_id": True, "author": True}
results = col.find(filter=query, projection=projection)
for one in results:
print(one)

print(">>> 用字典指定去掉哪些字段")
query = {}
projection = {"_id": False, "author": False}
results = col.find(query, projection=projection)
for one in results:
print(one)

print(">>> 用列表指定要显示哪几个字段")
query = {}
projection = ["author", "title"]
results = col.find(filter=query, projection=projection)
for one in results:
print(one)

print(">>> 指定范围,大于等于,小于等于")
query = {"age": {"$gte": 10, "$lte": 30}}
projection = None
results = col.find(filter=query, projection=projection)
for one in results:
print(one)

print(">>> 不同字段,并列条件")
query = {"author": "Sitoi", "age": 22}
projection = None
results = col.find(filter=query, projection=projection)
for one in results:
print(one)

print(">>> 相同字段,并列条件")
# 错误:
query = {"age": {"$gt": 50}, "age": {"$lt": 100}}
# 正确:
query = {"age": {"$gte": 10, "$lte": 20}}
projection = None
results = col.find(filter=query, projection=projection)
for one in results:
print(one)

print(">>> 不同字段,或条件")
query = {"$or": [{"age": 22}, {"author": "blog"}]}
projection = None
results = col.find(filter=query, projection=projection)
for one in results:
print(one)

print(">>> 相同字段,或条件")
query = {"$or": [{"age": 22}, {"age": 18}]}
projection = None
results = col.find(filter=query, projection=projection)
for one in results:
print(one)

print(">>> 字段不存在")
query = {"text": None}
projection = None
results = col.find(filter=query, projection=projection)
for one in results:
print(one)

print(">>> 字段存在")
query = {"text": {"$ne": None}}
projection = None
results = col.find(filter=query, projection=projection)
for one in results:
print(one)

print(">>> 正则查询")
query = {"author": {"$regex": "^S.*"}}
projection = None
results = col.find(filter=query, projection=projection)
for one in results:
print(one)

print(">>> 计数")
query = {}
count = col.count_documents(filter=query)
print(count)

print(">>> 排序")
results = col.find().sort([("author", 1), ("title", -1)])
for one in results:
print(one)

print(">>> 跳过")
results = col.find().skip(1)
for one in results:
print(one)

print(">>> 限制")
results = col.find().limit(1)
for one in results:
print(one)

print(">>> 更新单个文档")
query = {"age": 18}
update = {"$set": {"age": 20}}
modified_count = col.update_one(filter=query, update=update, upsert=False).modified_count
print(modified_count)

print(">>> 更新多个文档")
query = {"text": "Sitoi Blog"}
update = {"$set": {"text": "Sitoi PyMongo"}}
modified_count = col.update_many(filter=query, update=update, upsert=False).modified_count
print(modified_count)

print(">>> 删除单个文档")
query = {"author": "Sitoi"}
delete_count = col.delete_one(filter=query).deleted_count
print(delete_count)

print(">>> 删除多个文档")
query = {}
delete_count = col.delete_many(filter=query).deleted_count
print(delete_count)