MongoDB快速开始（V6.0）

标签：V6.0 MongoDB db genres collection movies 文档 快速 find

1. 切换数据库

显示当前数据库

db

切换数据库

use examples

2. 插入文档

MongoDB stores documents in collections. Collections are analogous to tables in relational databases. If a collection does not exist, MongoDB creates the collection when you first store data for that collection.

db.movies.insertMany([
   {
      title: 'Titanic',
      year: 1997,
      genres: [ 'Drama', 'Romance' ],
      rated: 'PG-13',
      languages: [ 'English', 'French', 'German', 'Swedish', 'Italian', 'Russian' ],
      released: ISODate("1997-12-19T00:00:00.000Z"),
      awards: {
         wins: 127,
         nominations: 63,
         text: 'Won 11 Oscars. Another 116 wins & 63 nominations.'
      },
      cast: [ 'Leonardo DiCaprio', 'Kate Winslet', 'Billy Zane', 'Kathy Bates' ],
      directors: [ 'James Cameron' ]
   },
   {
      title: 'The Dark Knight',
      year: 2008,
      genres: [ 'Action', 'Crime', 'Drama' ],
      rated: 'PG-13',
      languages: [ 'English', 'Mandarin' ],
      released: ISODate("2008-07-18T00:00:00.000Z"),
      awards: {
         wins: 144,
         nominations: 106,
         text: 'Won 2 Oscars. Another 142 wins & 106 nominations.'
      },
      cast: [ 'Christian Bale', 'Heath Ledger', 'Aaron Eckhart', 'Michael Caine' ],
      directors: [ 'Christopher Nolan' ]
   }
])

3. 查询所有文档

To select the documents from a collection, you can use the db.collection.find() method. To select all documents in the collection, pass an empty document as the query filter document to the method.

In the shell, copy and paste the following to return all documents in the movies collection.

db.movies.find( { } )

4. 过滤数据

查找导演为“Christopher Nolan”的文档

db.movies.find( { "directors": "Christopher Nolan" } );

查找2000年前上映的文档

db.movies.find( { "released": { $lt: ISODate("2000-01-01") } } );

查找获奖数目超过一百的文档

db.movies.find( { "awards.wins": { $gt: 100 } } );

查找语言为中文或者日语的电影文档

db.movies.find( { "languages": { $in: [ "Japanese", "Mandarin" ] } } )

5. 投影字段（Project Field）

查询文档，只返回标题、导演和年份字段

db.movies.find( { }, { "title": 1, "directors": 1, "year": 1 } );

查询文档，返回标题和分类字段，忽略id字段

db.movies.find( { }, { "_id": 0, "title": 1, "genres": 1 } );

6. 聚合查询

While find() operations are useful for data retrieval, the aggregation pipeline allows you to manipulate data, perform calculations, and write more expressive queries than simple CRUD operations.

统计所有电影类型的的数量

db.movies.aggregate( [
   { $unwind: "$genres" },
   {
     $group: {
       _id: "$genres",
       genreCount: { $count: { } }
     }
   },
   { $sort: { "genreCount": -1 } }
] )

标签：V6.0,MongoDB,db,genres,collection,movies,文档,快速,find
From： https://www.cnblogs.com/llazycat/p/16905339.html