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:mongodbin>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

> post1 = {"title":"learn MongoDB", "author":"Wilber", "date":new Date()}
{
        "title" : "learn MongoDB",
        "author" : "Wilber",
        "date" : ISODate("2014-11-29T06:19:32.556Z")
}
> db.blog.posts.insert(post1)
> db.blog.posts.find()
{ "_id" : ObjectId("5479657a421b7f1536cfb1f7"), "title" : "learn MongoDB", "author" : "Wilber", "date" : ISODate("2014-1
1-29T06:19:32.556Z") }
> show collections
blog.posts
system.indexes
>

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。

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

同时，remove操作可以支持条件删除。

> db.blog.posts.find()
{ "_id" : ObjectId("547967c1421b7f1536cfb1fe"), "title" : "learn MongoDB", "author" : "Wilber", "date" : ISODate("2014-1
1-29T06:29:21.318Z") }
{ "_id" : ObjectId("547967c1421b7f1536cfb1ff"), "title" : "learn English", "author" : "Will", "date" : ISODate("2014-11-
29T06:29:21.349Z") }
{ "_id" : ObjectId("547967c1421b7f1536cfb200"), "title" : "learn C#", "author" : "Li", "date" : ISODate("2014-11-29T06:2
9:21.365Z") }
{ "_id" : ObjectId("547967c2421b7f1536cfb201"), "title" : "learn SQL", "author" : "July", "date" : ISODate("2014-11-29T0
6:29:21.380Z") }
>
>
> db.blog.posts.remove({"author":"Will"})
> db.blog.posts.find()
{ "_id" : ObjectId("547967c1421b7f1536cfb1fe"), "title" : "learn MongoDB", "author" : "Wilber", "date" : ISODate("2014-1
1-29T06:29:21.318Z") }
{ "_id" : ObjectId("547967c1421b7f1536cfb200"), "title" : "learn C#", "author" : "Li", "date" : ISODate("2014-11-29T06:2
9:21.365Z") }
{ "_id" : ObjectId("547967c2421b7f1536cfb201"), "title" : "learn SQL", "author" : "July", "date" : ISODate("2014-11-29T0
6:29:21.380Z") }
>

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。

> post1.detailInfo = {"author":"Wilber","description":"this is a post about MongoDB"}
{ "author" : "Wilber", "description" : "this is a post about MongoDB" }
> delete post1.author
true
> db.blog.posts.update({"author":"Wilber"}, post1)
> db.blog.posts.find({"detailInfo.author":"Wilber"})
{ "_id" : ObjectId("547971c5421b7f1536cfb202"), "title" : "learn MongoDB", "date" : ISODate("2014-11-29T07:12:05.560Z"),
 "detailInfo" : { "author" : "Wilber", "description" : "this is a post about MongoDB" } }
>

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。

> db.blog.posts.update({"author":"Li"}, {$set: {"title":"how to learn C#"}})
> db.blog.posts.find({"author":"Li"})
{ "_id" : ObjectId("547971c5421b7f1536cfb204"), "author" : "Li", "date" : ISODate("2014-11-29T07:12:05.591Z"), "title" :
 "how to learn C#" }
> db.blog.posts.update({"author":"Li"}, {$set: {"age":27}})
> db.blog.posts.find({"author":"Li"})
{ "_id" : ObjectId("547971c5421b7f1536cfb204"), "age" : 27, "author" : "Li", "date" : ISODate("2014-11-29T07:12:05.591Z"
), "title" : "how to learn C#" }
>

$addToSet, $push, $pop：这三个都是对数组的操作，$addToSet能够避免重复添加

> comments = []
[ ]
> comment0 = {"score": 70, "content":"just so so"}
{ "score" : 70, "content" : "just so so" }
> comment1 = {"score": 90, "content":"very good"}
{ "score" : 90, "content" : "very good" }
>
> db.blog.posts.update({"author":"Li"}, {$set: {"comments": comments}})
> db.blog.posts.update({"author":"Li"}, {$set: {"comments.0": comment0}})
> db.blog.posts.update({"author":"Li"}, {$set: {"comments.1": comment1}})
> db.blog.posts.update({"author":"Li"}, {$addToSet: {"comments": comment1}})
> db.blog.posts.find({"author":"Li"})
{ "_id" : ObjectId("547971c5421b7f1536cfb204"), "age" : 27, "author" : "Li", "comments" : [     {   "score" : 70,
"content" : "just so so" },     {       "score" : 90,   "content" : "very good" } ], "date" : ISODate("2014-11-29T07:12:
05.591Z"), "title" : "how to learn C#" }
> db.blog.posts.update({"author":"Li"}, {$push: {"comments": comment1}})
> db.blog.posts.find({"author":"Li"})
{ "_id" : ObjectId("547971c5421b7f1536cfb204"), "age" : 27, "author" : "Li", "comments" : [     {   "score" : 70,
"content" : "just so so" },     {       "score" : 90,   "content" : "very good" },      {       "score" : 90,   "content
" : "very good" } ], "date" : ISODate("2014-11-29T07:12:05.591Z"), "title" : "how to learn C#" }
> db.blog.posts.update({"author":"Li"}, {$pop: {"comments": comment1}})
> db.blog.posts.find({"author":"Li"})
{ "_id" : ObjectId("547971c5421b7f1536cfb204"), "age" : 27, "author" : "Li", "comments" : [     {   "score" : 70,
"content" : "just so so" },     {       "score" : 90,   "content" : "very good" } ], "date" : ISODate("2014-11-29T07:12:
05.591Z"), "title" : "how to learn C#" }
>

$inc：这个跟$set的用法类似，只不过$inc是专门针对数字操作的。

> db.blog.posts.update({"author":"Li"}, {$inc: {"comments.1.score": 5}})
> db.blog.posts.find({"author":"Li"})
{ "_id" : ObjectId("547971c5421b7f1536cfb204"), "age" : 27, "author" : "Li", "comments" : [     {   "score" : 70,
"content" : "just so so" },     {       "score" : 95,   "content" : "very good" } ], "date" : ISODate("2014-11-29T07:12:
05.591Z"), "title" : "how to learn C#" }
>

$unset：这个命令是用来删除指定键的。

> db.blog.posts.update({"author":"Li"}, {$unset: {"comments": 1}})
> db.blog.posts.find({"author":"Li"})
{ "_id" : ObjectId("547971c5421b7f1536cfb204"), "age" : 27, "author" : "Li", "date" : ISODate("2014-11-29T07:12:05.591Z"
), "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。

> db.blog.posts.update({"author":"June"}, {"author": "June", "title": "C++ introduction"}, true)
> db.blog.posts.find({"author":"June"})
{ "_id" : ObjectId("5479781d217928d2be69552c"), "author" : "June", "title" : "C++ introduction" }
>

arg4：这个参数可以设置是否批量更新

> db.blog.posts.insert(post1)
> db.blog.posts.find({"detailInfo.author":"Wilber"})
{ "_id" : ObjectId("547971c5421b7f1536cfb202"), "title" : "learn MongoDB", "date" : ISODate("2014-11-29T07:12:05.560Z"),
 "detailInfo" : { "author" : "Wilber", "description" : "this is a post about MongoDB" } }
{ "_id" : ObjectId("54797864421b7f1536cfb206"), "title" : "learn MongoDB", "date" : ISODate("2014-11-29T07:12:05.560Z"),
 "detailInfo" : { "author" : "Wilber", "description" : "this is a post about MongoDB" } }
> db.blog.posts.update({"detailInfo.author":"Wilber"}, {$set: {"title":"how to learn MongoDB"}}, false, true)
>
> db.blog.posts.find({"detailInfo.author":"Wilber"})
{ "_id" : ObjectId("54797864421b7f1536cfb206"), "date" : ISODate("2014-11-29T07:12:05.560Z"), "detailInfo" : { "author"
: "Wilber", "description" : "this is a post about MongoDB" }, "title" : "how to learn MongoDB" }
{ "_id" : ObjectId("547971c5421b7f1536cfb202"), "date" : ISODate("2014-11-29T07:12:05.560Z"), "detailInfo" : { "author"
: "Wilber", "description" : "this is a post about MongoDB" }, "title" : "how to learn MongoDB" }
>

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。

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