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Mongodb入门与实践

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Mongodb入门与实践

Mac安装MongoDB

brew install mongodb

使用Homebrew成功安装MongoDB

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To have launchd start mongodb now and restart at login:
  brew services start mongodb
Or, if you don't want/need a background service you can just run:
  mongod --config /usr/local/etc/mongod.conf

Mac启动MongoDB

sudo mongod --config /usr/local/etc/mongod.conf

Mac连接MongoDB，另打开一个终端

mongo

MongoDB基本操作CRUD

创建文档

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> show dbs # 查看数据库列表
admin     0.000GB
local     0.000GB
tutorial  0.000GB
> db # 查看当前所在数据库
test
> use myblog # 选择数据库
switched to db blog
> db
myblog
> post = {"title" : "My Blog Post",
... "content" : "Here's my blog post",
... "date" : new Date()} # 创建变量，表示我们的MongoDB文档
{
	"title" : "My Blog Post",
	"content" : "Here's my blog post",
	"date" : ISODate("2017-08-22T03:03:11.266Z")
}
> db.blog.insert(post) # 插入数据，将MongoDB文档保存到blog集合
WriteResult({ "nInserted" : 1 })
> users = [{"uid" : 1}, {"uid" : 2}, {"uid" : 3}]
[ { "uid" : 1 }, { "uid" : 2 }, { "uid" : 3 } ]
> db.blog.insert(users) # 批量插入，接收的参数是一个文档数组
BulkWriteResult({
	"writeErrors" : [ ],
	"writeConcernErrors" : [ ],
	"nInserted" : 3,
	"nUpserted" : 0,
	"nMatched" : 0,
	"nModified" : 0,
	"nRemoved" : 0,
	"upserted" : [ ]
})
> db.blog.find()
{ "_id" : ObjectId("599e39e0a159b0cdf87feb8e"), "uid" : 1 }
{ "_id" : ObjectId("599e39e0a159b0cdf87feb8f"), "uid" : 2 }
{ "_id" : ObjectId("599e39e0a159b0cdf87feb90"), "uid" : 3 }
> show collections; # 查看集合列表
food
users
>

读取文档

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> db.blog.find() # 查看多个文档，最多显示20个，"_id"为额外添加的键
{ "_id" : ObjectId("599b9f05a159b0cdf87feb8d"), "title" : "My Blog Post", "content" : "Here's my blog post", "date" : ISODate("2017-08-22T03:03:11.266Z") }
> db.blog.findOne() # 查看1个文档
{
	"_id" : ObjectId("599b9f05a159b0cdf87feb8d"),
	"title" : "My Blog Post",
	"content" : "Here's my blog post",
	"date" : ISODate("2017-08-22T03:03:11.266Z")
}
>

更新文档之文档替换

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> post.comments = []
[ ]
> db.blog.update({title : "My Blog Post"}, post) # 更新文档，添加一个新的键comments，update接收两个参数，第一个是限定条件（必须唯一，否则更新就会失败），第二个是新的文档
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.blog.find()
{ "_id" : ObjectId("599b9f05a159b0cdf87feb8d"), "title" : "My Blog Post", "content" : "Here's my blog post", "date" : ISODate("2017-08-22T03:03:11.266Z"), "comments" : [ ] }
>

更新文档之使用修改器

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> post = {"id" : 1,
... "views" : 100
... }
{ "id" : 1, "views" : 100 }
> db.blog.insert(post)
WriteResult({ "nInserted" : 1 })
> db.blog.find()
{ "_id" : ObjectId("599e6555a159b0cdf87feb91"), "id" : 1, "views" : 100 }
> db.blog.update({"id" : 1},
... {"$inc" : {"views" : 1}}) # 使用$inc修改器增加已有的键views的值，如果该键不存在那就创建一个，$inc只能用于整型、长整型或双精度浮点型的值，使用修改器时，"_id"的值不能改变，其它键值，包括其它唯一索引的键，都是可以更改的。
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.blog.find()
{ "_id" : ObjectId("599e6555a159b0cdf87feb91"), "id" : 1, "views" : 101 }
> db.blog.update({"id" : 1}, {"$set" : {"comments" : 50}}) # $set修改器用于指定一个字段的值，如果这个字段不存在，则创建它。可用于增加自定义键或者更新已有的键值。
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.blog.find()
{ "_id" : ObjectId("599e6555a159b0cdf87feb91"), "id" : 1, "views" : 100, "comments" : 50 }
> db.blog.update({"id" : 1}, {"$unset" : {"comments" : 1}}) # 使用$unset修改器删除键
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.blog.find()
{ "_id" : ObjectId("599e6555a159b0cdf87feb91"), "id" : 1, "views" : 100 }
>

更新文档之数组修改器

$push

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> post = {"id" : 1,
... "title" : "My Blog Post",
... "content" : "Here's my blog post"
... }
{ "id" : 1, "title" : "My Blog Post", "content" : "Here's my blog post" }
> db.blog.insert(post)
WriteResult({ "nInserted" : 1 })
> db.blog.find()
{ "_id" : ObjectId("599f8c6da159b0cdf87feb92"), "id" : 1, "title" : "My Blog Post", "content" : "Here's my blog post" }
> db.blog.update({"title" : "My Blog Post"},
... {"$push" : {"comments" :
... {"name" : "joe", "content" : "nice post"}}}) # 如果数组已存在，$push会向已有的数组末尾加入一个元素，要是没有就创建一个新的数组
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.blog.find()
{ "_id" : ObjectId("599f8c6da159b0cdf87feb92"), "id" : 1, "title" : "My Blog Post", "content" : "Here's my blog post", "comments" : [ { "name" : "joe", "content" : "nice post" } ] }
> db.blog.update({"title" : "My Blog Post"},
... {"$push" : {"comments" :
... {"name" : "bob", "content" : "nice post"}}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.blog.find()
{ "_id" : ObjectId("599f8c6da159b0cdf87feb92"), "id" : 1, "title" : "My Blog Post", "content" : "Here's my blog post", "comments" : [ { "name" : "joe", "content" : "nice post" }, { "name" : "bob", "content" : "nice post" } ] }
>

$each

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> db.blog.update({"title" : "My Blog Post"},
... {"$push" : {"tags" : {"$each" : ["tag1", "tag2"]}}}) # 使用$each子操作符，可以通过一次$push操作添加多个值，如果指定的数组只含有一个元素，那这个操作符就等同于没有使用$each的普通$push操作
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.blog.find()
{ "_id" : ObjectId("599f8c6da159b0cdf87feb92"), "id" : 1, "title" : "My Blog Post", "content" : "Here's my blog post", "comments" : [ { "name" : "joe", "content" : "nice post" }, { "name" : "bob", "content" : "nice post" } ], "tags" : [ "tag1", "tag2" ] }
>

$slice

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> post = {"title" : "My Blog Post",
... "content" : "Here's my blog"}
{ "title" : "My Blog Post", "content" : "Here's my blog" }
> db.blog.insert(post)
WriteResult({ "nInserted" : 1 })
> db.blog.find()
{ "_id" : ObjectId("599f9a09a159b0cdf87feb93"), "title" : "My Blog Post", "content" : "Here's my blog" }
> db.blog.update({"title" : "My Blog Post"},
... {"$push" : {"tags" : {"$each" : ["tag1", "tag2", "tag3"],
... "$slice" : -2}}}) # $slice和$push组合在一起使用，可以保证数组不超过最大长度（2），如果数组元素数量小于最大长度（2），那么所有元素都会保留，如果数组元素数量大于最大长度，那么只有最后最大长度数量（2）个元素会保留，注意$slice的值必须是负整数,且不能单独与$push配合使用，必须使用$each
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.blog.find()
{ "_id" : ObjectId("599f9a09a159b0cdf87feb93"), "title" : "My Blog Post", "content" : "Here's my blog", "tags" : [ "tag2", "tag3" ] }
>

$sort

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> db.blog.update({"title" : "My Blog Post"},
... {"$push" : {"$tags" : {"$each" : ["tags4", "tags5", "tags6", "tags7", "tags8", "tags9", "tags10"],
... "$slice" : -5,
... "$sort" : {"tags" : -1}}}}) # 可以在$slice清理元素之前使用$sort排序，不能单独与$push配合使用，必须使用$each
> db.blog.find()
{ "_id" : ObjectId("599f9a09a159b0cdf87feb93"), "title" : "My Blog Post", "content" : "Here's my blog", "tags" : [ "tags6", "tags7", "tags8", "tags9", "tags10" ] }
>

将数组作为数据集使用

$ne

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> users = {"admin" : ["admin1", "admin2"],
... "member" : ["member1", "member2"]}
{
	"admin" : [
		"admin1",
		"admin2"
	],
	"member" : [
		"member1",
		"member2"
	]
}
> db.users.insert(users)
WriteResult({ "nInserted" : 1 })
> db.users.find()
{ "_id" : ObjectId("599fe3c5a159b0cdf87feb95"), "admin" : [ "admin1", "admin2" ], "member" : [ "member1", "member2" ] }
> db.users.update({"admin" : {"$ne" : "admin3"}},
... {$push : {"admin" : "admin3"}}) # 使用$ne查询要添加的数组元素是否在数组中已经存在，如果不存在，就添加进去
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.users.find()
{ "_id" : ObjectId("599fe3c5a159b0cdf87feb95"), "admin" : [ "admin1", "admin2", "admin3" ], "member" : [ "member1", "member2" ] }
> db.users.update({"admin" : {"$ne" : "admin3"}}, {$push : {"admin" : "admin3"}})
WriteResult({ "nMatched" : 0, "nUpserted" : 0, "nModified" : 0 })
> db.users.find()
{ "_id" : ObjectId("599fe3c5a159b0cdf87feb95"), "admin" : [ "admin1", "admin2", "admin3" ], "member" : [ "member1", "member2" ] }
>

$addToSet

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> users = {"username" : "bob",
... "email" : ["bob@qq.com", "bob@gmail.com"]}
{ "username" : "bob", "email" : [ "bob@qq.com", "bob@gmail.com" ] }
> db.users.insert(users)
WriteResult({ "nInserted" : 1 })
> db.users.find()
{ "_id" : ObjectId("599fe8a3a159b0cdf87feb96"), "username" : "bob", "email" : [ "bob@qq.com", "bob@gmail.com" ] }
> db.users.update({"username" : "bob"},
... {"$addToSet" : {"email" : "bob@qq.com"}}) # 使用$addToSet可以避免插入重复元素
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 0 })
> db.users.find()
{ "_id" : ObjectId("599fe8a3a159b0cdf87feb96"), "username" : "bob", "email" : [ "bob@qq.com", "bob@gmail.com" ] }
> db.users.update({"username" : "bob"},
... {"$addToSet" : {"email" : "bob@hotmail.com"}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.users.find()
{ "_id" : ObjectId("599fe8a3a159b0cdf87feb96"), "username" : "bob", "email" : [ "bob@qq.com", "bob@gmail.com", "bob@hotmail.com" ] }
> db.users.update({"username" : "bob"},
... {"$addToSet" : {"email" : {"$each" : ["bob@126.com", "bob@163.com"]}}}) # 使用$addToSet和$each组合起来，可以添加多个不同的值
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.users.find()
{ "_id" : ObjectId("599fe8a3a159b0cdf87feb96"), "username" : "bob", "email" : [ "bob@qq.com", "bob@gmail.com", "bob@hotmail.com", "bob@126.com", "bob@163.com" ] }
>

删除元素

$pop,$pull

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> db.users.update({"username" : "bob"},
... {"$pop" : {"email" : -1}}) # $pop从数组任何一段删除元素，正整数从末尾删除，负整数从头部删除
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.users.find()
{ "_id" : ObjectId("599fe8a3a159b0cdf87feb96"), "username" : "bob", "email" : [ "bob@gmail.com", "bob@hotmail.com", "bob@126.com", "bob@163.com" ] }
> db.users.update({"username" : "bob"}, {"$pop" : {"email" : 1}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.users.find()
{ "_id" : ObjectId("599fe8a3a159b0cdf87feb96"), "username" : "bob", "email" : [ "bob@gmail.com", "bob@hotmail.com", "bob@126.com" ] }
> db.users.update({"username" : "bob"},
... {"$pull" : {"email" : "bob@hotmail.com"}}) # $pull将匹配特定条件的文档全部删除
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.users.find()
{ "_id" : ObjectId("599fe8a3a159b0cdf87feb96"), "username" : "bob", "email" : [ "bob@gmail.com", "bob@126.com" ] }
>

基于位置的数组修改器

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> db.users.update({"username" : "bob"},
... {"$set" : {"email.0" : "bob@163.com"}}) # 可以将下标直接作为键来选择元素
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.users.findOne()
{
	"_id" : ObjectId("599fe8a3a159b0cdf87feb96"),
	"username" : "bob",
	"email" : [
		"bob@163.com",
		"bob@126.com"
	]
}
>

upsert

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> db.users.findOne()
{
	"_id" : ObjectId("599fe8a3a159b0cdf87feb96"),
	"username" : "bob",
	"email" : [
		"bob@163.com",
		"bob@126.com"
	]
}
> db.users.update({"username" : "bob"}, {"$inc" : {"score" : 80}}, true) # 第三个参数true表示这是个upsert，upsert是个特殊的更新，如果没有找到符合更新条件的文档，就会以这个条件和更新文档为基础，创建一个新的文档。如果找到了匹配的文档，则正常更新。
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.users.findOne()
{
	"_id" : ObjectId("599fe8a3a159b0cdf87feb96"),
	"username" : "bob",
	"email" : [
		"bob@163.com",
		"bob@126.com"
	],
	"score" : 80
}
>

更新多个文档

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> db.users.find()
{ "_id" : ObjectId("599fe8a3a159b0cdf87feb96"), "username" : "bob", "email" : [ "bob@163.com", "bob@126.com" ], "score" : 160 }
{ "_id" : ObjectId("59acf1ffa159b0cdf87feb97"), "username" : "joy", "email" : [ "joy@126.com", "joy@163.com" ], "score" : 160 }
{ "_id" : ObjectId("59acf261a159b0cdf87feb98"), "username" : "lucy", "email" : [ "lucy@126.com", "lucy@163.com" ], "score" : 160 }
> db.users.update({"score" : 160}, {"$set" : {"score" : 100}}, false, true) # 默认情况下，更新只能对匹配条件的第一个文档执行操作。如果多个文档符合条件，只有第一个文档会被更新，其它文档不会发生变化。要更新所有匹配文档，可以将update的第四个参数设置为true。注意：第3个参数表示更新是否是upsert更新。
WriteResult({ "nMatched" : 3, "nUpserted" : 0, "nModified" : 3 })
> db.users.find()
{ "_id" : ObjectId("599fe8a3a159b0cdf87feb96"), "username" : "bob", "email" : [ "bob@163.com", "bob@126.com" ], "score" : 100 }
{ "_id" : ObjectId("59acf1ffa159b0cdf87feb97"), "username" : "joy", "email" : [ "joy@126.com", "joy@163.com" ], "score" : 100 }
{ "_id" : ObjectId("59acf261a159b0cdf87feb98"), "username" : "lucy", "email" : [ "lucy@126.com", "lucy@163.com" ], "score" : 100 }
> db.users.update({"score" : 100}, {"$set" : {"score" : 60}}, false, true)
WriteResult({ "nMatched" : 3, "nUpserted" : 0, "nModified" : 3 })
> db.runCommand({getLastError : 1}) # 运行getLastError命令（可以理解为返回最后一次操作的相关信息）。键n的值就是被更新的数量，updatedExisting为true，表示对已有的文档进行更新。
{
	"connectionId" : 1,
	"updatedExisting" : true,
	"n" : 3,
	"syncMillis" : 0,
	"writtenTo" : null,
	"err" : null,
	"ok" : 1
}
>

返回被更新的文档findAndModify

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> db.users.find()
{ "_id" : ObjectId("599fe8a3a159b0cdf87feb96"), "username" : "bob", "email" : [ "bob@163.com", "bob@126.com" ], "score" : 60 }
{ "_id" : ObjectId("59acf1ffa159b0cdf87feb97"), "username" : "joy", "email" : [ "joy@126.com", "joy@163.com" ], "score" : 60 }
{ "_id" : ObjectId("59acf261a159b0cdf87feb98"), "username" : "lucy", "email" : [ "lucy@126.com", "lucy@163.com" ], "score" : 60 }
> db.runCommand({"findAndModify" : "users",
... "query" : {"score" : 60},
... "sort" : {"score" : -1},
... "update" : {"$set" : {"score" : 100}}}) # 字段说明：findAndModify字符串，集合名；query查询文档，用于检索文档的条件；sort排序结果的条件；update修改器文档，用于对匹配的文档进行更新（update和remove必须且只能指定一个）；remove布尔类型，表示是否删除文档（remove和update必须且只能指定一个）；new布尔类型，表示返回更新前的文档还是更新后的文档，默认是更新前的文档；fields文档中需要返回的字段（可选）；upsert布尔类型，值为true时表示这是一个upsert，默认是false。
{
	"lastErrorObject" : {
		"updatedExisting" : true,
		"n" : 1
	},
	"value" : {
		"_id" : ObjectId("599fe8a3a159b0cdf87feb96"),
		"username" : "bob",
		"email" : [
			"bob@163.com",
			"bob@126.com"
		],
		"score" : 60
	},
	"ok" : 1
}
> db.users.find()
{ "_id" : ObjectId("599fe8a3a159b0cdf87feb96"), "username" : "bob", "email" : [ "bob@163.com", "bob@126.com" ], "score" : 100 }
{ "_id" : ObjectId("59acf1ffa159b0cdf87feb97"), "username" : "joy", "email" : [ "joy@126.com", "joy@163.com" ], "score" : 60 }
{ "_id" : ObjectId("59acf261a159b0cdf87feb98"), "username" : "lucy", "email" : [ "lucy@126.com", "lucy@163.com" ], "score" : 60 }
>

删除文档

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> db.blog.remove({title : "My Blog Post"}) # remove将文档从数据库中永久删除，接收一个限定条件的文档作为参数，如果没有使用任何参数，会将集合内的所有文档全部删除，但不会删除集合本省，也不会删除集合的元信息，缺点是比drop删除速度慢
WriteResult({ "nRemoved" : 1 })
> db.blog.find()
>

drop删除

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> db.blog.drop() # 比remove删除速度快，缺点是不能指定任何限定条件，整个集合和元数据都被删除了
true
> db.blog.findOne()
null
>

查询

find简介

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> db.users.find() # 空的查询文档，会匹配集合的全部内容
{ "_id" : ObjectId("599fe8a3a159b0cdf87feb96"), "username" : "bob", "email" : [ "bob@163.com", "bob@126.com" ], "score" : 100 }
{ "_id" : ObjectId("59acf1ffa159b0cdf87feb97"), "username" : "joy", "email" : [ "joy@126.com", "joy@163.com" ], "score" : 100 }
{ "_id" : ObjectId("59acf261a159b0cdf87feb98"), "username" : "lucy", "email" : [ "lucy@126.com", "lucy@163.com" ], "score" : 60 }
> db.users.find({"score" : 100}) # 向查询文档中添加键/值对时，就意味着限定了查询条件
{ "_id" : ObjectId("599fe8a3a159b0cdf87feb96"), "username" : "bob", "email" : [ "bob@163.com", "bob@126.com" ], "score" : 100 }
{ "_id" : ObjectId("59acf1ffa159b0cdf87feb97"), "username" : "joy", "email" : [ "joy@126.com", "joy@163.com" ], "score" : 100 }
> db.users.find({"username" : "joy", "score" : 100}) # 可以向查询文档中添加多个键/值对，用逗号分隔，多个查询条件组合在一起，会被解释为条件1AND条件2...AND条件N
{ "_id" : ObjectId("59acf1ffa159b0cdf87feb97"), "username" : "joy", "email" : [ "joy@126.com", "joy@163.com" ], "score" : 100 }
> db.users.find({}, {"username" : 1, "email" : 1}) # 通过第二个参数可以指定想要返回的键，值为1表示返回，值为0表示剔除
{ "_id" : ObjectId("599fe8a3a159b0cdf87feb96"), "username" : "bob", "email" : [ "bob@163.com", "bob@126.com" ] }
{ "_id" : ObjectId("59acf1ffa159b0cdf87feb97"), "username" : "joy", "email" : [ "joy@126.com", "joy@163.com" ] }
{ "_id" : ObjectId("59acf261a159b0cdf87feb98"), "username" : "lucy", "email" : [ "lucy@126.com", "lucy@163.com" ] }
> db.users.find({}, {"username" : 1, "email" : 1, "_id" : 0})
{ "username" : "bob", "email" : [ "bob@163.com", "bob@126.com" ] }
{ "username" : "joy", "email" : [ "joy@126.com", "joy@163.com" ] }
{ "username" : "lucy", "email" : [ "lucy@126.com", "lucy@163.com" ] }
>

查询条件

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> db.users.find({"score" : {"$lt" : 100}}) # $lt小于
{ "_id" : ObjectId("59acf261a159b0cdf87feb98"), "username" : "lucy", "email" : [ "lucy@126.com", "lucy@163.com" ], "score" : 60 }
> db.users.find({"score" : {"$lte" : 100}}) # $lte小于等于
{ "_id" : ObjectId("599fe8a3a159b0cdf87feb96"), "username" : "bob", "email" : [ "bob@163.com", "bob@126.com" ], "score" : 100 }
{ "_id" : ObjectId("59acf1ffa159b0cdf87feb97"), "username" : "joy", "email" : [ "joy@126.com", "joy@163.com" ], "score" : 100 }
{ "_id" : ObjectId("59acf261a159b0cdf87feb98"), "username" : "lucy", "email" : [ "lucy@126.com", "lucy@163.com" ], "score" : 60 }
> db.users.find({"score" : {"$gt" : 60}}) # $gt大于
{ "_id" : ObjectId("599fe8a3a159b0cdf87feb96"), "username" : "bob", "email" : [ "bob@163.com", "bob@126.com" ], "score" : 100 }
{ "_id" : ObjectId("59acf1ffa159b0cdf87feb97"), "username" : "joy", "email" : [ "joy@126.com", "joy@163.com" ], "score" : 100 }
> db.users.find({"score" : {"$gte" : 60}}) # $gte大于等于
{ "_id" : ObjectId("599fe8a3a159b0cdf87feb96"), "username" : "bob", "email" : [ "bob@163.com", "bob@126.com" ], "score" : 100 }
{ "_id" : ObjectId("59acf1ffa159b0cdf87feb97"), "username" : "joy", "email" : [ "joy@126.com", "joy@163.com" ], "score" : 100 }
{ "_id" : ObjectId("59acf261a159b0cdf87feb98"), "username" : "lucy", "email" : [ "lucy@126.com", "lucy@163.com" ], "score" : 60 }
> db.users.find({"score" : {"$lte" : 100, "$gte" : 60}}) # 组合使用
{ "_id" : ObjectId("599fe8a3a159b0cdf87feb96"), "username" : "bob", "email" : [ "bob@163.com", "bob@126.com" ], "score" : 100 }
{ "_id" : ObjectId("59acf1ffa159b0cdf87feb97"), "username" : "joy", "email" : [ "joy@126.com", "joy@163.com" ], "score" : 100 }
{ "_id" : ObjectId("59acf261a159b0cdf87feb98"), "username" : "lucy", "email" : [ "lucy@126.com", "lucy@163.com" ], "score" : 60 }
> db.users.find({"username" : {"$ne" : 'joy'}}) # $ne不等于
{ "_id" : ObjectId("599fe8a3a159b0cdf87feb96"), "username" : "bob", "email" : [ "bob@163.com", "bob@126.com" ], "score" : 100 }
{ "_id" : ObjectId("59acf261a159b0cdf87feb98"), "username" : "lucy", "email" : [ "lucy@126.com", "lucy@163.com" ], "score" : 60 }
>

OR查询

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> db.users.find({"score" : {"$in" : [100, 60]}}) # $in匹配多个值
{ "_id" : ObjectId("599fe8a3a159b0cdf87feb96"), "username" : "bob", "email" : [ "bob@163.com", "bob@126.com" ], "score" : 100 }
{ "_id" : ObjectId("59acf1ffa159b0cdf87feb97"), "username" : "joy", "email" : [ "joy@126.com", "joy@163.com" ], "score" : 100 }
{ "_id" : ObjectId("59acf261a159b0cdf87feb98"), "username" : "lucy", "email" : [ "lucy@126.com", "lucy@163.com" ], "score" : 60 }
> db.users.find({"score" : {"$nin" : [60, 80]}}) # $nin不匹配多个值
{ "_id" : ObjectId("599fe8a3a159b0cdf87feb96"), "username" : "bob", "email" : [ "bob@163.com", "bob@126.com" ], "score" : 100 }
{ "_id" : ObjectId("59acf1ffa159b0cdf87feb97"), "username" : "joy", "email" : [ "joy@126.com", "joy@163.com" ], "score" : 100 }
> db.users.find({"$or" : [{"username" : "lucy"}, {"score" : 100}]}) # $or包含多个匹配条件
{ "_id" : ObjectId("599fe8a3a159b0cdf87feb96"), "username" : "bob", "email" : [ "bob@163.com", "bob@126.com" ], "score" : 100 }
{ "_id" : ObjectId("59acf1ffa159b0cdf87feb97"), "username" : "joy", "email" : [ "joy@126.com", "joy@163.com" ], "score" : 100 }
{ "_id" : ObjectId("59acf261a159b0cdf87feb98"), "username" : "lucy", "email" : [ "lucy@126.com", "lucy@163.com" ], "score" : 60 }
> db.users.find({"$or" : [{"username" : {"$in" : ["bob", "joy"]}}, {"score" : 60}]}) # $or可以包含其它条件
{ "_id" : ObjectId("599fe8a3a159b0cdf87feb96"), "username" : "bob", "email" : [ "bob@163.com", "bob@126.com" ], "score" : 100 }
{ "_id" : ObjectId("59acf1ffa159b0cdf87feb97"), "username" : "joy", "email" : [ "joy@126.com", "joy@163.com" ], "score" : 100 }
{ "_id" : ObjectId("59acf261a159b0cdf87feb98"), "username" : "lucy", "email" : [ "lucy@126.com", "lucy@163.com" ], "score" : 60 }
>

$not

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> db.users.find({"score" : {"$not" : {"$in" : [60, 80]}}}) # $not用来查找那些与特定模式不匹配的文档
{ "_id" : ObjectId("599fe8a3a159b0cdf87feb96"), "username" : "bob", "email" : [ "bob@163.com", "bob@126.com" ], "score" : 100 }
{ "_id" : ObjectId("59acf1ffa159b0cdf87feb97"), "username" : "joy", "email" : [ "joy@126.com", "joy@163.com" ], "score" : 100 }
>

特定类型查询

null

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> db.users.insert({"username" : "lily", "email" : null, "score" : 80})
WriteResult({ "nInserted" : 1 })
> db.users.find()
{ "_id" : ObjectId("599fe8a3a159b0cdf87feb96"), "username" : "bob", "email" : [ "bob@163.com", "bob@126.com" ], "score" : 100 }
{ "_id" : ObjectId("59acf1ffa159b0cdf87feb97"), "username" : "joy", "email" : [ "joy@126.com", "joy@163.com" ], "score" : 100 }
{ "_id" : ObjectId("59acf261a159b0cdf87feb98"), "username" : "lucy", "email" : [ "lucy@126.com", "lucy@163.com" ], "score" : 60 }
{ "_id" : ObjectId("59b89d85a159b0cdf87feb99"), "username" : "lily", "email" : null, "score" : 80 }
> db.users.find({"email" : null}) # null不仅会匹配某个键的值为null的文档，而且还会匹配不包含这个键的文档
{ "_id" : ObjectId("59b89d85a159b0cdf87feb99"), "username" : "lily", "email" : null, "score" : 80 }
> db.users.find({"tel" : null})
{ "_id" : ObjectId("599fe8a3a159b0cdf87feb96"), "username" : "bob", "email" : [ "bob@163.com", "bob@126.com" ], "score" : 100 }
{ "_id" : ObjectId("59acf1ffa159b0cdf87feb97"), "username" : "joy", "email" : [ "joy@126.com", "joy@163.com" ], "score" : 100 }
{ "_id" : ObjectId("59acf261a159b0cdf87feb98"), "username" : "lucy", "email" : [ "lucy@126.com", "lucy@163.com" ], "score" : 60 }
{ "_id" : ObjectId("59b89d85a159b0cdf87feb99"), "username" : "lily", "email" : null, "score" : 80 }
> db.users.find({"email" : {"$in" : [null], "$exists" : true}})
{ "_id" : ObjectId("59b89d85a159b0cdf87feb99"), "username" : "lily", "email" : null, "score" : 80 }
> db.users.find({"tel" : {"$in" : [null], "$exists" : true}}) # 如果仅想匹配键值为null的文档，既要检查该键的值是否为null，还要通过$exists判定键值已存在
>

查询数组

$all

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> db.food.insert({"fruit" : ["apple", "banana", "peach"]})
WriteResult({ "nInserted" : 1 })
> db.food.find({"fruit" : "banana"}) # 查询数组元素和查询标量值是一样的。
{ "_id" : ObjectId("59b8a605a159b0cdf87feb9a"), "fruit" : [ "apple", "banana", "peach" ] }
> db.food.insert({"fruit" : ["apple", "kumquat", "orange"]})
WriteResult({ "nInserted" : 1 })
> db.food.insert({"fruit" : ["cherry", "banana", "apple"]})
WriteResult({ "nInserted" : 1 })
> db.food.find({"fruit" : {"$all" : ["apple", "banana"]}}) # 使用$all可以通过多个元素匹配数组
{ "_id" : ObjectId("59b8a605a159b0cdf87feb9a"), "fruit" : [ "apple", "banana", "peach" ] }
{ "_id" : ObjectId("59b8a8bba159b0cdf87feb9c"), "fruit" : [ "cherry", "banana", "apple" ] }
> db.food.find({"fruit.2" : "peach"}) # 查询数组特定位置的元素，需要使用key.index语法指定下标，数组下标都是从0开始
{ "_id" : ObjectId("59b8a605a159b0cdf87feb9a"), "fruit" : [ "apple", "banana", "peach" ] }
>

$size

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> db.food.find({"fruit" : {"$size" : 3}}) # $size查询特定长度的数组
{ "_id" : ObjectId("59b8a605a159b0cdf87feb9a"), "fruit" : [ "apple", "banana", "peach" ] }
{ "_id" : ObjectId("59b8a89aa159b0cdf87feb9b"), "fruit" : [ "apple", "kumquat", "orange" ] }
{ "_id" : ObjectId("59b8a8bba159b0cdf87feb9c"), "fruit" : [ "cherry", "banana", "apple" ] }
> db.food.find({"fruit" : {"$size" : 2}})
>

$slice操作符

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> db.blogs.insert({"title" : "This is my blog title", "content" : "This is my blog content", "comments" : [{"name" : "joe", "email" : "joe@example.com", "content" : "nice post."}, {"name" : "bob", "email" : "bob@example.com", "content" : "good post."}, {"name" : "lucy", "email" : "lucy@example.com", "content" : "beautiful post."}]})
WriteResult({ "nInserted" : 1 })
> db.blogs.findOne()
{
	"_id" : ObjectId("59c0b66aa159b0cdf87feb9d"),
	"title" : "This is my blog title",
	"content" : "This is my blog content",
	"comments" : [
		{
			"name" : "joe",
			"email" : "joe@example.com",
			"content" : "nice post."
		},
		{
			"name" : "bob",
			"email" : "bob@example.com",
			"content" : "good post."
		},
		{
			"name" : "lucy",
			"email" : "lucy@example.com",
			"content" : "beautiful post."
		}
	]
}
> db.blogs.findOne({}, {"comments" : {"$slice" : 2}}) # $slice操作符可以返回某个键匹配的数组元素的一个子集。例如，我们返回前2条评论。
{
	"_id" : ObjectId("59c0b66aa159b0cdf87feb9d"),
	"title" : "This is my blog title",
	"content" : "This is my blog content",
	"comments" : [
		{
			"name" : "joe",
			"email" : "joe@example.com",
			"content" : "nice post."
		},
		{
			"name" : "bob",
			"email" : "bob@example.com",
			"content" : "good post."
		}
	]
}
> db.blogs.findOne({}, {"comments" : {"$slice" : -2}}) # 返回后2条评论
{
	"_id" : ObjectId("59c0b66aa159b0cdf87feb9d"),
	"title" : "This is my blog title",
	"content" : "This is my blog content",
	"comments" : [
		{
			"name" : "bob",
			"email" : "bob@example.com",
			"content" : "good post."
		},
		{
			"name" : "lucy",
			"email" : "lucy@example.com",
			"content" : "beautiful post."
		}
	]
}
> db.blogs.findOne({}, {"comments" : {"$slice" : [2, 3]}}) # 返回第3个到第5个评论，如果数组不够5个元素，则返回第3个后面的所有元素。
{
	"_id" : ObjectId("59c0b66aa159b0cdf87feb9d"),
	"title" : "This is my blog title",
	"content" : "This is my blog content",
	"comments" : [
		{
			"name" : "lucy",
			"email" : "lucy@example.com",
			"content" : "beautiful post."
		}
	]
}
>

返回一个匹配的数组元素

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> db.blogs.find({"comments.name" : "bob"}, {"comments.$" : 1}) # 使用$操作符返回与查询条件相匹配的任意一个数组元素，注意，这样只会返回第一个匹配的文档。
{ "_id" : ObjectId("59c0b66aa159b0cdf87feb9d"), "comments" : [ { "name" : "bob", "email" : "bob@example.com", "content" : "good post." } ] }
>

数组和范围查询的相互作用

感谢赞赏.

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