MongoDB文档的增删改操作
上一篇文章中介绍了MongoDB的一些基本知识，同时看到了怎么启动一个MongoDB服务，并且通过MongoDB自带的shell工具连接到了服务器。
这一次，就通过MongoDB shell介绍一下对文档的增删改操作。
增加新文档
接着上一篇文章，打开一个MongoDB shell。
通过“show dbs”可以看到所有的数据库。然后我们通过“use blog”切换到blog数据库来开始下面的演示。
使用“db”命令显示当前正在使用的数据库。
1 C:\mongodb\bin>mongo.exe
2 MongoDB shell version: 2.4.6
3 connecting to: test
4 > show dbs
5 local 0.078125GB
6 >
7 > use blog
8 switched to db blog
9 >
10 > db
11 blog
12 >
接下来就开始新建文档，插入文档的操作了
1 > post1 = {"title":"learn MongoDB", "author":"Wilber", "date":new Date()} 2 { 3 "title" : "learn MongoDB", 4 "author" : "Wilber", 5 "date" : ISODate("2014-11-29T06:19:32.556Z") 6 } 7 > db.blog.posts.insert(post1) 8 > db.blog.posts.find() 9 { "_id" : ObjectId("5479657a421b7f1536cfb1f7"), "title" : "learn MongoDB", "author" : "Wilber", "date" : ISODate("2014-1 10 1-29T06:19:32.556Z") } 11 > show collections 12 blog.posts 13 system.indexes 14 >
通过相同的方式插入新的文档。
post2 = {"title":"learn English", "author":"Will", "date":new Date()}
post3 = {"title":"learn C#", "author":"Li", "date":new Date()}
post4 = {"title":"learn SQL", "author":"July", "date":new Date()}
删除文档
通过remove操作，可以对文档进行删除。如果没有任何参数，remove将会删除collection中所有的文档，而且删除操作是不可逆的，所以要小心操作。
1 > db.blog.posts.remove() 2 > db.blog.posts.find() 3 >
同时，remove操作可以支持条件删除。
1 > db.blog.posts.find() 2 { "_id" : ObjectId("547967c1421b7f1536cfb1fe"), "title" : "learn MongoDB", "author" : "Wilber", "date" : ISODate("2014-1 3 1-29T06:29:21.318Z") } 4 { "_id" : ObjectId("547967c1421b7f1536cfb1ff"), "title" : "learn English", "author" : "Will", "date" : ISODate("2014-11- 5 29T06:29:21.349Z") } 6 { "_id" : ObjectId("547967c1421b7f1536cfb200"), "title" : "learn C#", "author" : "Li", "date" : ISODate("2014-11-29T06:2 7 9:21.365Z") } 8 { "_id" : ObjectId("547967c2421b7f1536cfb201"), "title" : "learn SQL", "author" : "July", "date" : ISODate("2014-11-29T0 9 6:29:21.380Z") } 10 > 11 > 12 > db.blog.posts.remove({"author":"Will"}) 13 > db.blog.posts.find() 14 { "_id" : ObjectId("547967c1421b7f1536cfb1fe"), "title" : "learn MongoDB", "author" : "Wilber", "date" : ISODate("2014-1 15 1-29T06:29:21.318Z") } 16 { "_id" : ObjectId("547967c1421b7f1536cfb200"), "title" : "learn C#", "author" : "Li", "date" : ISODate("2014-11-29T06:2 17 9:21.365Z") } 18 { "_id" : ObjectId("547967c2421b7f1536cfb201"), "title" : "learn SQL", "author" : "July", "date" : ISODate("2014-11-29T0 19 6:29:21.380Z") } 20 >
更新文档
可以通过update方法更新数据库中的文档，update有两个参数，一个是查询文档，用来找出要更新的文档，另一个是修改器文档，描述多找到的文档进行怎样的更新。
文档的更新可以分为两种：文档替换和使用修改器更新
文档替换
当文档的模式变化很大的时候，一般都是采用文档替换的方式进行文档更新。
1 > post1.detailInfo = {"author":"Wilber","description":"this is a post about MongoDB"} 2 { "author" : "Wilber", "description" : "this is a post about MongoDB" } 3 > delete post1.author 4 true 5 > db.blog.posts.update({"author":"Wilber"}, post1) 6 > db.blog.posts.find({"detailInfo.author":"Wilber"}) 7 { "_id" : ObjectId("547971c5421b7f1536cfb202"), "title" : "learn MongoDB", "date" : ISODate("2014-11-29T07:12:05.560Z"), 8 "detailInfo" : { "author" : "Wilber", "description" : "this is a post about MongoDB" } } 9 >
修改器更新
对于只需要部分更新的文档，通过修改器更新会很方便。直接上例子。
$set: 修改文档的一个指定键的值，如果没有则创建。
1 > db.blog.posts.update({"author":"Li"}, {$set: {"title":"how to learn C#"}}) 2 > db.blog.posts.find({"author":"Li"}) 3 { "_id" : ObjectId("547971c5421b7f1536cfb204"), "author" : "Li", "date" : ISODate("2014-11-29T07:12:05.591Z"), "title" : 4 "how to learn C#" } 5 > db.blog.posts.update({"author":"Li"}, {$set: {"age":27}}) 6 > db.blog.posts.find({"author":"Li"}) 7 { "_id" : ObjectId("547971c5421b7f1536cfb204"), "age" : 27, "author" : "Li", "date" : ISODate("2014-11-29T07:12:05.591Z" 8 ), "title" : "how to learn C#" } 9 >
$addToSet, $push, $pop：这三个都是对数组的操作，$addToSet能够避免重复添加
1 > comments = [] 2 [ ] 3 > comment0 = {"score": 70, "content":"just so so"} 4 { "score" : 70, "content" : "just so so" } 5 > comment1 = {"score": 90, "content":"very good"} 6 { "score" : 90, "content" : "very good" } 7 > 8 > db.blog.posts.update({"author":"Li"}, {$set: {"comments": comments}}) 9 > db.blog.posts.update({"author":"Li"}, {$set: {"comments.0": comment0}}) 10 > db.blog.posts.update({"author":"Li"}, {$set: {"comments.1": comment1}}) 11 > db.blog.posts.update({"author":"Li"}, {$addToSet: {"comments": comment1}}) 12 > db.blog.posts.find({"author":"Li"}) 13 { "_id" : ObjectId("547971c5421b7f1536cfb204"), "age" : 27, "author" : "Li", "comments" : [ { "score" : 70, 14 "content" : "just so so" }, { "score" : 90, "content" : "very good" } ], "date" : ISODate("2014-11-29T07:12: 15 05.591Z"), "title" : "how to learn C#" } 16 > db.blog.posts.update({"author":"Li"}, {$push: {"comments": comment1}}) 17 > db.blog.posts.find({"author":"Li"}) 18 { "_id" : ObjectId("547971c5421b7f1536cfb204"), "age" : 27, "author" : "Li", "comments" : [ { "score" : 70, 19 "content" : "just so so" }, { "score" : 90, "content" : "very good" }, { "score" : 90, "content 20 " : "very good" } ], "date" : ISODate("2014-11-29T07:12:05.591Z"), "title" : "how to learn C#" } 21 > db.blog.posts.update({"author":"Li"}, {$pop: {"comments": comment1}}) 22 > db.blog.posts.find({"author":"Li"}) 23 { "_id" : ObjectId("547971c5421b7f1536cfb204"), "age" : 27, "author" : "Li", "comments" : [ { "score" : 70, 24 "content" : "just so so" }, { "score" : 90, "content" : "very good" } ], "date" : ISODate("2014-11-29T07:12: 25 05.591Z"), "title" : "how to learn C#" } 26 >
$inc：这个跟$set的用法类似，只不过$inc是专门针对数字操作的。
1 > db.blog.posts.update({"author":"Li"}, {$inc: {"comments.1.score": 5}}) 2 > db.blog.posts.find({"author":"Li"}) 3 { "_id" : ObjectId("547971c5421b7f1536cfb204"), "age" : 27, "author" : "Li", "comments" : [ { "score" : 70, 4 "content" : "just so so" }, { "score" : 95, "content" : "very good" } ], "date" : ISODate("2014-11-29T07:12: 5 05.591Z"), "title" : "how to learn C#" } 6 >
$unset：这个命令是用来删除指定键的。
1 > db.blog.posts.update({"author":"Li"}, {$unset: {"comments": 1}}) 2 > db.blog.posts.find({"author":"Li"}) 3 { "_id" : ObjectId("547971c5421b7f1536cfb204"), "age" : 27, "author" : "Li", "date" : ISODate("2014-11-29T07:12:05.591Z" 4 ), "title" : "how to learn C#" }
update(arg1, arg2, arg3, arg4)
上面已经介绍了update的前两个参数的含义和用法，其实update命令还有两个参数。
arg3：这个参数代表upsert用法；如果这个参数设置为true，那么就会使用upsert的方式更新文档。
1 > db.blog.posts.update({"author":"June"}, {"author": "June", "title": "C++ introduction"}, true) 2 > db.blog.posts.find({"author":"June"}) 3 { "_id" : ObjectId("5479781d217928d2be69552c"), "author" : "June", "title" : "C++ introduction" } 4 >
arg4：这个参数可以设置是否批量更新
1 > db.blog.posts.insert(post1) 2 > db.blog.posts.find({"detailInfo.author":"Wilber"}) 3 { "_id" : ObjectId("547971c5421b7f1536cfb202"), "title" : "learn MongoDB", "date" : ISODate("2014-11-29T07:12:05.560Z"), 4 "detailInfo" : { "author" : "Wilber", "description" : "this is a post about MongoDB" } } 5 { "_id" : ObjectId("54797864421b7f1536cfb206"), "title" : "learn MongoDB", "date" : ISODate("2014-11-29T07:12:05.560Z"), 6 "detailInfo" : { "author" : "Wilber", "description" : "this is a post about MongoDB" } } 7 > db.blog.posts.update({"detailInfo.author":"Wilber"}, {$set: {"title":"how to learn MongoDB"}}, false, true) 8 > 9 > db.blog.posts.find({"detailInfo.author":"Wilber"}) 10 { "_id" : ObjectId("54797864421b7f1536cfb206"), "date" : ISODate("2014-11-29T07:12:05.560Z"), "detailInfo" : { "author" 11 : "Wilber", "description" : "this is a post about MongoDB" }, "title" : "how to learn MongoDB" } 12 { "_id" : ObjectId("547971c5421b7f1536cfb202"), "date" : ISODate("2014-11-29T07:12:05.560Z"), "detailInfo" : { "author" 13 : "Wilber", "description" : "this is a post about MongoDB" }, "title" : "how to learn MongoDB" } 14 >
总结
这篇文章主要介绍了通过MongoDB shell对数据库文档进行增删改操作，接下来会介绍查询的操作。
Ps: 附件包含了本文中的所有命令作为参考。
https://files.cnblogs.com/wilber2013/test.js
