文章出处：http://blog.csdn.net/leshami/article/details/55049891

MongoDB在文档上支持数组,其次数组上可以实现嵌套,以及数组元素也可以文档.因此,对于文档上数组的操作,MongoDB提供很多种不同的方式,包括数组的查询,数组元素的添加删除等等.本文主要描述数组查询,供大家参考.

一、演示环境及数据

> db.version() 3.2.11 > db.users.insertMany( [ { _id: 1,name: "sue",age: 19,type: 1,status: "P",favorites: { artist: "Picasso",food: "pizza" },finished: [ 17,3 ],badges: [ "blue","black" ],points: [ { points: 85,bonus: 20 },{ points: 85,bonus: 10 } ] },{ _id: 2,name: "bob",age: 42,status: "A",favorites: { artist: "Miro",food: "meringue" },finished: [ 11,25 ],badges: [ "green" ],{ points: 64,bonus: 12 } ] },{ _id: 3,name: "ahn",age: 22,type: 2,favorites: { artist: "Cassatt",food: "cake" },finished: [ 6 ],"red" ],points: [ { points: 81,bonus: 8 },{ points: 55,bonus: 20 } ] },{ _id: 4,name: "xi",age: 34,status: "D",favorites: { artist: "Chagall",food: "chocolate" },finished: [ 5,11 ],badges: [ "red",points: [ { points: 53,bonus: 15 },{ points: 51,bonus: 15 } ] },{ _id: 5,name: "xyz",age: 23,favorites: { artist: "Noguchi",food: "nougat" },finished: [ 14,6 ],badges: [ "orange" ],points: [ { points: 71,{ _id: 6,name: "abc",age: 43,favorites: { food: "pizza",artist: "Picasso" },finished: [ 18,12 ],badges: [ "black","blue" ],points: [ { points: 78,{ points: 57,bonus: 7 } ] } ] )123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990

二、演示数组查询

1、数组元素模糊匹配

//如下示例,数组字段badges每个包含该元素black的文档都将被返回 > db.users.find({badges:"black"},{"_id":1,badges:1}) { "_id" : 1,"badges" : [ "blue","black" ] } { "_id" : 4,"badges" : [ "red","black" ] } { "_id" : 6,"badges" : [ "black","blue" ] }12345

2、数组元素精确(全)匹配

//如下示例,数组字段badges的值为["black","blue"]的文档才能被返回(数组元素值和元素顺序全匹配) > db.users.find({badges:["black","blue"]},badges:1}) { "_id" : 6,"blue" ] }123

3、通过数组下标返回指定的文档

数组的下标从0开始,指定下标值则返回对应的文档 //如下示例,返回数组badges中第一个元素值为black的文档 > db.users.find({"badges.1":"black"},"black" ] }12345

4、范围条件任意元素匹配查询

//查询数组finished的元素值既大于15,又小于20的文档 > db.users.find( { finished: { $gt: 15,$lt: 20}},finished:1}) { "_id" : 1,"finished" : [ 17,3 ] } { "_id" : 2,"finished" : [ 11,25 ] } { "_id" : 6,"finished" : [ 18,12 ] } //下面插入一个新的文档,仅包含单个数组元素 > db.users.insert({"_id":7,finished:[19]}) WriteResult({ "nInserted" : 1 }) //再次查询,新增的文档也被返回 > db.users.find( { finished: { $gt: 15,12 ] } { "_id" : 7,"finished" : [ 19 ] }12345678910111213141516

5、数组内嵌文档查询

//查询数组points元素1内嵌文档键points的值小于等于55的文档(精确匹配) > db.users.find( { 'points.0.points': { $lte: 55}},points:1}) { "_id" : 4,"points" : [ { "points" : 53,"bonus" : 15 },{ "points" : 51,"bonus" : 15 } ] } //查询数组points内嵌文档键points的值小于等于55的文档,此处通过.成员的方式实现 > db.users.find( { 'points.points': { $lte: 55}},points:1}) { "_id" : 3,"points" : [ { "points" : 81,"bonus" : 8 },{ "points" : 55,"bonus" : 20 } ] } { "_id" : 4,"bonus" : 15 } ] }12345678

6、数组元素操作符$elemMatch

作用：数组值中至少一个元素满足所有指定的匹配条件 语法： { <field>: { $elemMatch: { <query1>,<query2>,... } } } 说明： 如果查询为单值查询条件,即只有<query1>,则无需指定$elemMatch //如下示例,为无需指定$elemMatch情形 //查询数组内嵌文档字段points.points的值为85的文档 > db.users.find( { "points.points": 85},points:1}) { "_id" : 1,"points" : [ { "points" : 85,"bonus" : 20 },{ "points" : 85,"bonus" : 10 } ] } { "_id" : 2,{ "points" : 64,"bonus" : 12 } ] } > db.users.find( { points:{ $elemMatch:{points:85}}},"bonus" : 12 } ] } //单数组查询($elemMatch示例) > db.scores.insertMany( ... [{ _id: 1,results: [ 82,85,88 ] },//Author : Leshami ... { _id: 2,results: [ 75,88,89 ] }]) //Blog : http://blog.csdn.net/leshami { "acknowledged" : true,"insertedIds" : [ 1,2 ] } > db.scores.find({ results: { $elemMatch: { $gte: 80,$lt: 85 } } }) { "_id" : 1,"results" : [ 82,88 ] } //数组内嵌文档查询示例($elemMatch示例) //查询数组内嵌文档字段points.points的值大于等于70,并且bonus的值20的文档(要求2个条件都必须满足) //也就是说数组points的至少需要一个元素同时满足以上2个条件,这样的结果文档才会返回 //下面的查询数组值{ "points" : 55,"bonus" : 20 }满足条件 > db.users.find( { points: { $elemMatch: { points: { $lte: 70 },bonus: 20}}},"bonus" : 20 } ] }12345678910111213141516171819202122232425262728

7、数组元素操作符$all

作用：数组值中满足所有指定的匹配条件,不考虑多出的元素以及元素顺序问题 语法：{ <field>: { $all: [ <value1>,<value2> ... ] } } > db.users.find({badges:{$all:["black","blue"]}},"black" ] } //此处查询的结果不考虑元素的顺序 { "_id" : 6,"blue" ] } //只要包含这2个元素的集合都被返回 等价的操作方式 > db.users.find({$and:[{badges:"blue"},{badges:"black"}]},"blue" ] }1234567891011

8、数组元素操作符$size

作用：返回元素个数总值等于指定值的文档 语法：db.collection.find( { field: { $size: 2 } } ); 说明：$size不支持指定范围,而是一个具体的值.此外针对$size,没有相关可用的索引来提高性能 //查询数组badges包含1个元素的文档  > db.users.find({badges:{$size:1}},badges:1}) { "_id" : 2,"badges" : [ "green" ] } { "_id" : 5,"badges" : [ "orange" ] } //查询数组badges包含2个元素的文档 > db.users.find({badges:{$size:2}},"black" ] } { "_id" : 3,"red" ] } { "_id" : 4,"blue" ] }123456789101112131415

9、数组元素操作符$slice

作用：用于返回指定位置的数组元素值的子集(是数值元素值得一部分,不是所有的数组元素值) 示例：db.collection.find( { field: value },{ array: {$slice: count } } );  //创建演示文档 > db.blog.insert( ... {_id:1,title:"mongodb unique index",... comment: [ ... {"name" : "joe","content" : "nice post."},... {"name" : "bob","content" : "good post."},... {"name" : "john","content" : "greatly."}]} ... ) WriteResult({ "nInserted" : 1 }) //通过$slice返回集合中comment数组第一条评论 > db.blog.find({},{comment:{$slice:1}}).pretty() { "_id" : 1,"title" : "mongodb unique index","comment" : [ { "name" : "joe","content" : "nice post." } ] } //通过$slice返回集合中comment数组最后一条评论 > db.blog.find({},{comment:{$slice:-1}}).pretty() { "_id" : 1,"comment" : [ { "name" : "john","content" : "greatly." } ] } //通过$slice返回集合中comment数组特定的评论(可以理解为分页) //如下查询,返回的是第2-3条评论,第一条被跳过 > db.blog.find({},{comment:{$slice:[1,3]}}).pretty() { "_id" : 1,"comment" : [ { "name" : "bob","content" : "good post." },{ "name" : "john","content" : "greatly." } ] }1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253545556

10、$占位符,返回数组中第一个匹配的数组元素值(子集)

使用样式： db.collection.find( { <array>: <value> ... },{ "<array>.$": 1 } ) db.collection.find( { <array.field>: <value> ...},{ "<array>.$": 1 } ) 使用示例 > db.students.insertMany([ { "_id" : 1,"semester" : 1,"grades" : [ 70,87,90 ] },{ "_id" : 2,"grades" : [ 90,92 ] },{ "_id" : 3,"grades" : [ 85,100,{ "_id" : 4,"semester" : 2,"grades" : [ 79,80 ] },{ "_id" : 5,"grades" : [ 88,{ "_id" : 6,"grades" : [ 95,90,96 ] }])  //通过下面的查询可知,仅仅只有第一个大于等于85的元素值被返回 //也就是说$占位符返回的是数组的第一个匹配的值,是数组的子集 > db.students.find( { semester: 1,grades: { $gte: 85 } },... { "grades.$": 1 } ) { "_id" : 1,"grades" : [ 87 ] } { "_id" : 2,"grades" : [ 90 ] } { "_id" : 3,"grades" : [ 85 ] } > db.students.drop() //使用新的示例数据 > db.students.insertMany([ { "_id" : 7,semester: 3,"grades" : [ { grade: 80,mean: 75,std: 8 },{ grade: 85,mean: 90,std: 5 },{ grade: 90,mean: 85,std: 3 } ] },{ "_id" : 8,"grades" : [ { grade: 92,mean: 88,{ grade: 78,{ grade: 88,std: 3 } ] }]) //下面的查询中,数组的元素为内嵌文档,同样如此,数组元素第一个匹配的元素值被返回 > db.students.find( ... { "grades.mean": { $gt: 70 } },... { "grades.$": 1 } ... ) { "_id" : 7,"grades" : [ { "grade" : 80,"mean" : 75,"std" : 8 } ] } { "_id" : 8,"grades" : [ { "grade" : 92,"mean" : 88,"std" : 8 } ] }123456789101112131415161718192021222324252627282930313233343536373839404142

三、小结

a、数组查询有精确和模糊之分,精确匹配需要指定数据元素的全部值

b、数组查询可以通过下标的方式进行查询

c、数组内嵌套文档可以通过.成员的方式进行查询

d、数组至少一个元素满足所有指定的匹配条件可以使用$elemMatch

e、数组查询中返回元素的子集可以通过$slice以及占位符来实现f、all满足所有指定的匹配条件,不考虑多出的元素以及元素顺序问题

文章出处：http://blog.csdn.net/leshami/article/details/55049891