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mongodb查询

时间：2021-07-01 10:21:17 帮助过：14人阅读

这节来说说如何检索mongodb数据。首先向文档中插入一些数据。1. 插入数据 use ttlsa_comswitched to db ttlsa_com db.mediaCollection.insert({ "Type" : "Book", "Title" : "Definitive Guide to MongoDB, the", "ISBN" : "987-1-4302-3051-9", "Publisher"

这节来说说如何检索mongodb数据。首先向文档中插入一些数据。 1. 插入数据 
  1. > use ttlsa_com
  2. switched to db ttlsa_com
  3. > db.mediaCollection.insert({ "Type" : "Book", "Title" : "Definitive Guide to MongoDB, the", "ISBN" : "987-1-4302-3051-9", "Publisher" : "Apress", "Author": [ "Membrey, Peter", "Plugge, Eelco", "Hawkins, Tim" ] })
  4. > db.mediaCollection.insert({ "Type" : "CD", "Artist" : "Nirvana", "Title" : "Nevermind" })
  5. > db.mediaCollection.insert({ "Type" : "CD", "Artist" : "Nirvana", "Title" : "Nevermind", "Tracklist" : [ { "Track" : "1", "Title" : "Smells like teen spirit", "Length" : "5:02" }, { "Track" : "2", "Title" : "In Bloom", "Length" : "4:15" } ]})
  6. > db.mediaCollection.find()
  7. { "_id" : ObjectId("5353462f93efef02c962da71"), "Type" : "Book", "Title" : "Definitive Guide to MongoDB, the", "ISBN" : "987-1-4302-3051-9", "Publisher" : "Apress", "Author" : [ "Membrey, Peter", "Plugge, Eelco", "Hawkins, Tim" ] }
  8. { "_id" : ObjectId("5353462f93efef02c962da72"), "Type" : "CD", "Artist" : "Nirvana", "Title" : "Nevermind" }
  9. { "_id" : ObjectId("5353463193efef02c962da73"), "Type" : "CD", "Artist" : "Nirvana", "Title" : "Nevermind", "Tracklist" : [ { "Track" : "1", "Title" : "Smells like teen spirit", "Length" : "5:02" }, { "Track" : "2", "Title" : "In Bloom", "Length" : "4:15" } ] }
2. 检索 find函数是经常用到的一个。前面的文章也有介绍到。下面看看有选择性的检索，查看你感兴趣的数据。 检索"Artist" : "Nirvana"的数据： 
  1. > db.mediaCollection.find({"Artist" : "Nirvana"}).toArray()
  2. [
  3.         {
  4.                 "_id" : ObjectId("5353462f93efef02c962da72"),
  5.                 "Type" : "CD",
  6.                 "Artist" : "Nirvana",
  7.                 "Title" : "Nevermind"
  8.         },
  9.         {
  10.                 "_id" : ObjectId("5353463193efef02c962da73"),
  11.                 "Type" : "CD",
  12.                 "Artist" : "Nirvana",
  13.                 "Title" : "Nevermind",
  14.                 "Tracklist" : [
  15.                         {
  16.                                 "Track" : "1",
  17.                                 "Title" : "Smells like teen spirit",
  18.                                 "Length" : "5:02"
  19.                         },
  20.                         {
  21.                                 "Track" : "2",
  22.                                 "Title" : "In Bloom",
  23.                                 "Length" : "4:15"
  24.                         }
  25.                 ]
  26.         }
  27. ]
上面的查询虽说检索出"Artist" : "Nirvana"的数据，但是返回了全部列的信息，但是我只要查看Title和Tracklist.Title列 
  1. > db.mediaCollection.find({"Artist" : "Nirvana"}, {Title:1, "Tracklist.Title":1}).toArray()
  2. [
  3.         {
  4.                 "_id" : ObjectId("5353462f93efef02c962da72"),
  5.                 "Title" : "Nevermind"
  6.         },
  7.         {
  8.                 "_id" : ObjectId("5353463193efef02c962da73"),
  9.                 "Title" : "Nevermind",
  10.                 "Tracklist" : [
  11.                         {
  12.                                 "Title" : "Smells like teen spirit"
  13.                         },
  14.                         {
  15.                                 "Title" : "In Bloom"
  16.                         }
  17.                 ]
  18.         }
  19. ]
Title:1, "Tracklist.Title":1表示只返回这两列信息。升序。也可以反着来Title:0, "Tracklist.Title":0表示返回除了这两列的其他所有列信息。 注意：_id字段总是会返回。 3. ?使用逗号 当文档结构变的复杂时，如含有数组或嵌入对象文档，就需要使用到逗号，来检索嵌入在文档中的信息。 
  1. > db.mediaCollection.find({"Tracklist.Length":"5:02"}).toArray()
  2. [
  3.         {
  4.                 "_id" : ObjectId("5353463193efef02c962da73"),
  5.                 "Type" : "CD",
  6.                 "Artist" : "Nirvana",
  7.                 "Title" : "Nevermind",
  8.                 "Tracklist" : [
  9.                         {
  10.                                 "Track" : "1",
  11.                                 "Title" : "Smells like teen spirit",
  12.                                 "Length" : "5:02"
  13.                         },
  14.                         {
  15.                                 "Track" : "2",
  16.                                 "Title" : "In Bloom",
  17.                                 "Length" : "4:15"
  18.                         }
  19.                 ]
  20.         }
  21. ]
查询整个内嵌文档： 
  1. > db.mediaCollection.find({Tracklist:{"Length":"5:02"}}).toArray()
  2. [ ]
  3. > db.mediaCollection.find({Tracklist:{"Track" : "1","Title" : "Smells like teen spirit","Length":"5:02"}}).toArray()
  4. [
  5.         {
  6.                 "_id" : ObjectId("5353463193efef02c962da73"),
  7.                 "Type" : "CD",
  8.                 "Artist" : "Nirvana",
  9.                 "Title" : "Nevermind",
  10.                 "Tracklist" : [
  11.                         {
  12.                                 "Track" : "1",
  13.                                 "Title" : "Smells like teen spirit",
  14.                                 "Length" : "5:02"
  15.                         },
  16.                         {
  17.                                 "Track" : "2",
  18.                                 "Title" : "In Bloom",
  19.                                 "Length" : "4:15"
  20.                         }
  21.                 ]
  22.         }
  23. ]
  24. > db.mediaCollection.find({Tracklist:{"Track" : "1","Length" : "5:02","Title" : "Smells like teen spirit"}}).toArray()
  25. [ ]
查询整个文档需要全部列出内嵌文档的字段，且顺序要一致，否则匹配不到。 查询内嵌文档的多个字段。如查询有joe发表且分数在5分以上： 
  1. > db.mediaCollection.insert({ "content" : "...", "comments" : [ { "author" : "joe", "score" : 3, "comment" : "nice post" }, { "author" : "mary", "score" : 6, "comment" : "terrible post" } ] })
  2. > db.mediaCollection.find().toArray()
  3. [
  4.         {
  5.                 "_id" : ObjectId("5353462f93efef02c962da71"),
  6.                 "Type" : "Book",
  7.                 "Title" : "Definitive Guide to MongoDB, the",
  8.                 "ISBN" : "987-1-4302-3051-9",
  9.                 "Publisher" : "Apress",
  10.                 "Author" : [
  11.                         "Membrey, Peter",
  12.                         "Plugge, Eelco",
  13.                         "Hawkins, Tim"
  14.                 ]
  15.         },
  16.         {
  17.                 "_id" : ObjectId("5353462f93efef02c962da72"),
  18.                 "Type" : "CD",
  19.                 "Artist" : "Nirvana",
  20.                 "Title" : "Nevermind"
  21.         },
  22.         {
  23.                 "_id" : ObjectId("5353463193efef02c962da73"),
  24.                 "Type" : "CD",
  25.                 "Artist" : "Nirvana",
  26.                 "Title" : "Nevermind",
  27.                 "Tracklist" : [
  28.                         {
  29.                                 "Track" : "1",
  30.                                 "Title" : "Smells like teen spirit",
  31.                                 "Length" : "5:02"
  32.                         },
  33.                         {
  34.                                 "Track" : "2",
  35.                                 "Title" : "In Bloom",
  36.                                 "Length" : "4:15"
  37.                         }
  38.                 ]
  39.         },
  40.         {
  41.                 "_id" : ObjectId("5353681293efef02c962da7a"),
  42.                 "content" : "...",
  43.                 "comments" : [
  44.                         {
  45.                                 "author" : "joe",
  46.                                 "score" : 3,
  47.                                 "comment" : "nice post"
  48.                         },
  49.                         {
  50.                                 "author" : "mary",
  51.                                 "score" : 6,
  52.                                 "comment" : "terrible post"
  53.                         }
  54.                 ]
  55.         }
  56. ]
  57. > db.mediaCollection.find({"comments" : {"author" : "joe", "score" : {"$gte" : 5}}}).toArray()
  58. [ ]
  59. > db.mediaCollection.find({"comments.author" : "joe", "comments.score" : {"$gte" : 5}}).toArray()
  60. [
  61.         {
  62.                 "_id" : ObjectId("5353681293efef02c962da7a"),
  63.                 "content" : "...",
  64.                 "comments" : [
  65.                         {
  66.                                 "author" : "joe",
  67.                                 "score" : 3,
  68.                                 "comment" : "nice post"
  69.                         },
  70.                         {
  71.                                 "author" : "mary",
  72.                                 "score" : 6,
  73.                                 "comment" : "terrible post"
  74.                         }
  75.                 ]
  76.         }
  77. ]
上面的查询是不对的。 要正确的指定一组条件，而不是每个键，因此要使用到$elemMatch。这样就可以用来部分指定匹配数组中的单个内嵌文档的限定条件。正确的写法如下所示： 
  1. > db.mediaCollection.find({"comments" : {"$elemMatch" : {"author" : "joe", "score" : {"$gte" : 5}}}}).toArray()
  2. [ ]
对于数组： 
  1. > db.mediaCollection.find({"Author":"Membrey, Peter"}).toArray()
  2. [
  3.         {
  4.                 "_id" : ObjectId("5353462f93efef02c962da71"),
  5.                 "Type" : "Book",
  6.                 "Title" : "Definitive Guide to MongoDB, the",
  7.                 "ISBN" : "987-1-4302-3051-9",
  8.                 "Publisher" : "Apress",
  9.                 "Author" : [
  10.                         "Membrey, Peter",
  11.                         "Plugge, Eelco",
  12.                         "Hawkins, Tim"
  13.                 ]
  14.         }
  15. ]
正则表达式查询： 
  1. > db.mediaCollection.find({"Title":/MongoDB/i}).toArray()
  2. [
  3.         {
  4.                 "_id" : ObjectId("5353462f93efef02c962da71"),
  5.                 "Type" : "Book",
  6.                 "Title" : "Definitive Guide to MongoDB, the",
  7.                 "ISBN" : "987-1-4302-3051-9",
  8.                 "Publisher" : "Apress",
  9.                 "Author" : [
  10.                         "Membrey, Peter",
  11.                         "Plugge, Eelco",
  12.                         "Hawkins, Tim"
  13.                 ]
  14.         }
  15. ]
对检索结果进行Sort, Limit, 和Skip请看下节内容。

原文地址：mongodb查询, 感谢原作者分享。

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