MongoDB中常用的find

接着前一篇文章，下面主要介绍一下MongoDB中常用的find操作。

先打开MongoDB shell，通过下面一组命令插入一些数据。

 post1 = {"title":"learn MongoDB", "author":"Wilber", "date":new Date(), "score":}

 post2 = {"title":"learn English", "author":"Will", "date":new Date(), "score":}

 post3 = {"title":"learn C#", "author":"Li", "date":new Date(), "score":}

 post4 = {"title":"learn SQL", "author":"July", "date":new Date(), "score":}

 post5 = {"title":"learn Node", "author":"Wilber", "date":new Date(), "score":}

 db.blog.posts.insert(post1)

 db.blog.posts.insert(post2)

 db.blog.posts.insert(post3)

 db.blog.posts.insert(post4)

 db.blog.posts.insert(post5)

 users1 = ["Wilber", "Will", "June"]

 users2 = ["Will", "July", "Wilber"]

 users3 = ["James", "Jack", "Will"]

 db.blog.users.insert({"users":users1})

 db.blog.users.insert({"users":users2})

 db.blog.users.insert({"users":users3})

find（arg1，arg2）简介

find查询会返回一个Collection中文档的子集。关于find的两个参数，arg1表示匹配条件，arg2可以指定要返回的键。

直接上例子，对于arg2，可以通过设置值为0，来控制那些键不要显示

 > db.blog.posts.find({"author":"Will"})

 { "_id" : ObjectId("5479c9f2421b7f1536cfb208"), "title" : "learn English", "author" : "Will", "date" : ISODate("2014-11-

 29T13::.959Z"), "score" : 95 }

 > db.blog.posts.find({}, {"title":, "score":})

 { "_id" : ObjectId("5479c9f2421b7f1536cfb207"), "title" : "learn MongoDB", "score" :  }

 { "_id" : ObjectId("5479c9f2421b7f1536cfb208"), "title" : "learn English", "score" :  }

 { "_id" : ObjectId("5479c9f2421b7f1536cfb209"), "title" : "learn C#", "score" :  }

 { "_id" : ObjectId("5479c9f2421b7f1536cfb20a"), "title" : "learn SQL", "score" :  }

 { "_id" : ObjectId("5479c9f4421b7f1536cfb20b"), "title" : "learn Node", "score" :  }

 > db.blog.posts.find({}, {"date": })

 { "_id" : ObjectId("5479c9f2421b7f1536cfb207"), "title" : "learn MongoDB", "author" : "Wilber", "score" :  }

 { "_id" : ObjectId("5479c9f2421b7f1536cfb208"), "title" : "learn English", "author" : "Will", "score" :  }

 { "_id" : ObjectId("5479c9f2421b7f1536cfb209"), "title" : "learn C#", "author" : "Li", "score" :  }

 { "_id" : ObjectId("5479c9f2421b7f1536cfb20a"), "title" : "learn SQL", "author" : "July", "score" :  }

 { "_id" : ObjectId("5479c9f4421b7f1536cfb20b"), "title" : "learn Node", "author" : "Wilber", "score" :  }

常用查询条件

比较条件：$gt,$gte,$lt,$lte,$ne

 > db.blog.posts.find({"score":{"$gte":,"$lt":}})

 { "_id" : ObjectId("5479c9f2421b7f1536cfb207"), "title" : "learn MongoDB", "author" : "Wilber", "date" : ISODate("2014-1

 -29T13::.939Z"), "score" : 90 }

 { "_id" : ObjectId("5479c9f4421b7f1536cfb20b"), "title" : "learn Node", "author" : "Wilber", "date" : ISODate("2014-11-2

 9T13::.999Z"), "score" : 93 }

 > db.blog.posts.find({"author":{"$ne":"July"}})

 { "_id" : ObjectId("5479c9f2421b7f1536cfb207"), "title" : "learn MongoDB", "author" : "Wilber", "date" : ISODate("2014-1

 -29T13::.939Z"), "score" : 90 }

 { "_id" : ObjectId("5479c9f2421b7f1536cfb208"), "title" : "learn English", "author" : "Will", "date" : ISODate("2014-11-

 29T13::.959Z"), "score" : 95 }

 { "_id" : ObjectId("5479c9f2421b7f1536cfb209"), "title" : "learn C#", "author" : "Li", "date" : ISODate("2014-11-29T13:2

 :.979Z"), "score" : 80 }

 { "_id" : ObjectId("5479c9f4421b7f1536cfb20b"), "title" : "learn Node", "author" : "Wilber", "date" : ISODate("2014-11-2

 9T13::.999Z"), "score" : 93 }

 >

包含条件：$in,$nin

 > db.blog.posts.find({"author":{"$in":["Wilber","Will"]}})

 { "_id" : ObjectId("5479c9f2421b7f1536cfb207"), "title" : "learn MongoDB", "author" : "Wilber", "date" : ISODate("2014-1

 -29T13::.939Z"), "score" : 90 }

 { "_id" : ObjectId("5479c9f2421b7f1536cfb208"), "title" : "learn English", "author" : "Will", "date" : ISODate("2014-11-

 29T13::.959Z"), "score" : 95 }

 { "_id" : ObjectId("5479c9f4421b7f1536cfb20b"), "title" : "learn Node", "author" : "Wilber", "date" : ISODate("2014-11-2

 9T13::.999Z"), "score" : 93 }

 > db.blog.posts.find({"author":{"$nin":["Wilber","Will"]}})

 { "_id" : ObjectId("5479c9f2421b7f1536cfb209"), "title" : "learn C#", "author" : "Li", "date" : ISODate("2014-11-29T13:2

 :.979Z"), "score" : 80 }

 { "_id" : ObjectId("5479c9f2421b7f1536cfb20a"), "title" : "learn SQL", "author" : "July", "date" : ISODate("2014-11-29T1

 ::.989Z"), "score" : 70 }

 >

或操作：$or

 > db.blog.posts.find({"$or":[{"author":"Wilber"}, {"score":{"$gt":}}]})

 { "_id" : ObjectId("5479c9f2421b7f1536cfb207"), "title" : "learn MongoDB", "author" : "Wilber", "date" : ISODate("2014-1

 -29T13::.939Z"), "score" : 90 }

 { "_id" : ObjectId("5479c9f2421b7f1536cfb208"), "title" : "learn English", "author" : "Will", "date" : ISODate("2014-11-

 29T13::.959Z"), "score" : 95 }

 { "_id" : ObjectId("5479c9f4421b7f1536cfb20b"), "title" : "learn Node", "author" : "Wilber", "date" : ISODate("2014-11-2

 9T13::.999Z"), "score" : 93 }

 >

limit(),skip(),sort()

 > db.blog.posts.find().limit()

 { "_id" : ObjectId("5479c9f2421b7f1536cfb207"), "title" : "learn MongoDB", "author" : "Wilber", "date" : ISODate("2014-1

 -29T13::.939Z"), "score" : 90 }

 { "_id" : ObjectId("5479c9f2421b7f1536cfb208"), "title" : "learn English", "author" : "Will", "date" : ISODate("2014-11-

 29T13::.959Z"), "score" : 95 }

 > db.blog.posts.find().skip()

 { "_id" : ObjectId("5479c9f2421b7f1536cfb208"), "title" : "learn English", "author" : "Will", "date" : ISODate("2014-11-

 29T13::.959Z"), "score" : 95 }

 { "_id" : ObjectId("5479c9f2421b7f1536cfb209"), "title" : "learn C#", "author" : "Li", "date" : ISODate("2014-11-29T13:2

 :.979Z"), "score" : 80 }

 { "_id" : ObjectId("5479c9f2421b7f1536cfb20a"), "title" : "learn SQL", "author" : "July", "date" : ISODate("2014-11-29T1

 ::.989Z"), "score" : 70 }

 { "_id" : ObjectId("5479c9f4421b7f1536cfb20b"), "title" : "learn Node", "author" : "Wilber", "date" : ISODate("2014-11-2

 9T13::.999Z"), "score" : 93 }

 > db.blog.posts.find().sort({"athor":,"score":-})

 { "_id" : ObjectId("5479c9f2421b7f1536cfb208"), "title" : "learn English", "author" : "Will", "date" : ISODate("2014-11-

 29T13::.959Z"), "score" : 95 }

 { "_id" : ObjectId("5479c9f4421b7f1536cfb20b"), "title" : "learn Node", "author" : "Wilber", "date" : ISODate("2014-11-2

 9T13::.999Z"), "score" : 93 }

 { "_id" : ObjectId("5479c9f2421b7f1536cfb207"), "title" : "learn MongoDB", "author" : "Wilber", "date" : ISODate("2014-1

 -29T13::.939Z"), "score" : 90 }

 { "_id" : ObjectId("5479c9f2421b7f1536cfb209"), "title" : "learn C#", "author" : "Li", "date" : ISODate("2014-11-29T13:2

 :.979Z"), "score" : 80 }

 { "_id" : ObjectId("5479c9f2421b7f1536cfb20a"), "title" : "learn SQL", "author" : "July", "date" : ISODate("2014-11-29T1

 ::.989Z"), "score" : 70 }

 >

数组的查询

$all：通过多个元素匹配数组
支持“键.下标”方式的匹配
支持$size的方式匹配

 > db.blog.users.find({"users":"Will"})

 { "_id" : ObjectId("5479d03d421b7f1536cfb20c"), "users" : [  "Wilber",  "Will",  "June" ] }

 { "_id" : ObjectId("5479d03d421b7f1536cfb20d"), "users" : [  "Will",  "July",  "Wilber" ] }

 { "_id" : ObjectId("5479d03d421b7f1536cfb20e"), "users" : [  "James",  "Jack",  "Will" ] }

 > db.blog.users.find({"users": {"$all": ["Wilber", "Will"]}})

 { "_id" : ObjectId("5479d03d421b7f1536cfb20c"), "users" : [  "Wilber",  "Will",  "June" ] }

 { "_id" : ObjectId("5479d03d421b7f1536cfb20d"), "users" : [  "Will",  "July",  "Wilber" ] }

 > db.blog.users.find({"users": ["Wilber", "Will"]})

 > db.blog.users.find({"users.2":"Will"})

 { "_id" : ObjectId("5479d03d421b7f1536cfb20e"), "users" : [  "James",  "Jack",  "Will" ] }

 > db.blog.users.find({"users":{"$size":}})

 { "_id" : ObjectId("5479d03d421b7f1536cfb20c"), "users" : [  "Wilber",  "Will",  "June" ] }

 { "_id" : ObjectId("5479d03d421b7f1536cfb20d"), "users" : [  "Will",  "July",  "Wilber" ] }

 { "_id" : ObjectId("5479d03d421b7f1536cfb20e"), "users" : [  "James",  "Jack",  "Will" ] }

 >

null的含义

 > post5.z = null

 null

 > db.blog.posts.update({"title":"learn Node"}, post5)

 > db.blog.posts.find({"z":null})

 { "_id" : ObjectId("5479c9f2421b7f1536cfb207"), "title" : "learn MongoDB", "author" : "Wilber", "date" : ISODate("2014-1

 -29T13::.939Z"), "score" : 90 }

 { "_id" : ObjectId("5479c9f2421b7f1536cfb208"), "title" : "learn English", "author" : "Will", "date" : ISODate("2014-11-

 29T13::.959Z"), "score" : 95 }

 { "_id" : ObjectId("5479c9f2421b7f1536cfb209"), "title" : "learn C#", "author" : "Li", "date" : ISODate("2014-11-29T13:2

 :.979Z"), "score" : 80 }

 { "_id" : ObjectId("5479c9f2421b7f1536cfb20a"), "title" : "learn SQL", "author" : "July", "date" : ISODate("2014-11-29T1

 ::.989Z"), "score" : 70 }

 { "_id" : ObjectId("5479c9f4421b7f1536cfb20b"), "title" : "learn Node", "author" : "Wilber", "date" : ISODate("2014-11-2

 9T13::.999Z"), "score" : 93, "z" : null }

 > db.blog.posts.find({"z":{"$in":[null], "$exists": true}})

 { "_id" : ObjectId("5479c9f4421b7f1536cfb20b"), "title" : "learn Node", "author" : "Wilber", "date" : ISODate("2014-11-2

 9T13::.999Z"), "score" : 93, "z" : null }

 >

Ps:可以通过以下链接的到例子中的shell命令。

http://files.cnblogs.com/wilber2013/find.js

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