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  • MongoDB的简单使用查询操作

    MongoDB通过find()函数执行查询操作

    1.查找集合内的全部文档:

    db.media.find()

    系统返回:

    { "_id" : ObjectId("5aa47c1953350e04ddbd6fa3"), "Type" : "Book", "Title" : "Definitive Guide to MongoDB 3rd ed.", "ISBN" : "978-1-4842-1183-0", "Publisher" : "Apress", "Author" : [ "Hows,David", "Plugge,Eelco", "Membrey,Peter", "Hawkins,Tim" ] }
    { "_id" : ObjectId("5aa47dd553350e04ddbd6fa4"), "Type" : "CD", "Artist" : "Nirvana", "Title" : "Nevermind", "Tracklist" : [ { "Track" : "1", "Titie" : "Smells Like Teen Spirit", "Length" : "5:02" }, { "Track" : "2", "Title" : "In Bloom", "Length" : "4:15" } ] }

    显示出上篇文章我们添加的2个文档

    2.查找Nirvana的所有CD:

    db.media.find({Artist:"Nirvana"})

    系统返回:

    { "_id" : ObjectId("5aa47dd553350e04ddbd6fa4"), "Type" : "CD", "Artist" : "Nirvana", "Title" : "Nevermind", "Tracklist" : [ { "Track" : "1", "Titie" : "Smells Like Teen Spirit", "Length" : "5:02" }, { "Track" : "2", "Title" : "In Bloom", "Length" : "4:15" } ] }

    3.查找Nirvana的所有CD的标题:

    db.media.find({Artist:"Nirvana"},{Title:1})

    系统返回:

    { "_id" : ObjectId("5aa47dd553350e04ddbd6fa4"), "Title" : "Nevermind" }

    查找Nirvana的所有CD的非标题信息

    db.media.find({Artist:"Nirvana"},{Title:0})

    系统返回:

    { "_id" : ObjectId("5aa47dd553350e04ddbd6fa4"), "Type" : "CD", "Artist" : "Nirvana", "Tracklist" : [ { "Track" : "1", "Titie" : "Smells Like Teen Spirit", "Length" : "5:02" }, { "Track" : "2", "Title" : "In Bloom", "Length" : "4:15" } ] }

    4.查找内嵌对象文档的信息:

    db.media.find({"Tracklist.Title":"In Bloom"})

    系统将返回对应文档的全部信息

    { "_id" : ObjectId("5aa47dd553350e04ddbd6fa4"), "Type" : "CD", "Artist" : "Nirvana", "Title" : "Nevermind", "Tracklist" : [ { "Track" : "1", "Titie" : "Smells Like Teen Spirit", "Length" : "5:02" }, { "Track" : "2", "Title" : "In Bloom", "Length" : "4:15" } ] }

    5其他相关函数

      sort()排序函数 db.media.find().sort({Title:1})      #1为升序,-1为降序

      limit()限制返回结果的最大数目 db.media.find().limit(10)      #0表示返回所有结果

      skip()忽略集合中的前几个文档 db.media.find().skip(20)      

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  • 原文地址:https://www.cnblogs.com/chzhang1994/p/8543200.html
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