MongoDB：mongoDB Shell的基本操作

╰+哭是因爲堅強的太久メ 2022-04-23 15:06 249阅读 0赞

### 文章目录 ###

*  shell运行JS程序
 *  shell操作数据
 *   *  创建
     *  读取
     *  更新
     *  删除
 *  shell 帮助文档

# shell运行JS程序 #

1、进行数学运算

> x = 200
    200
    > x / 5;
    40

2、shell可以允许任何JaveScript程序，我们可以调用JaveScript的标准库

> Math.sin(Math.PI/2);
    1
    > new Date("2010/1/1")
    ISODate("2009-12-31T16:00:00Z")
    > new Date("2019/1/1")
    ISODate("2018-12-31T16:00:00Z")
    > "Hello World".replace("World", "MongoDB")
    Hello MongoDB

3、可以定义和调用JaveScript函数

> function factorial(n){
        
    ... if(n <= 1) return 1;
    ... return n + factorial(n-1);
    ... }
    > factorial(365);
    66795

# shell操作数据 #

## 创建 ##

1、创建一个局部变量post，内容是代表文档的JaveScript对象

> post = {"title":"My Blog Post",
    ... "content":"Here's my blog post.",
    ... "date":new Date()}
    {
    	"title" : "My Blog Post",
    	"content" : "Here's my blog post.",
    	"date" : ISODate("2019-03-17T09:12:51.098Z")
    }

2、使用insert将post文档保存到blog集合中

> db.blog.insert(post)
    WriteResult({
         "nInserted" : 1 })

3、查看

> db.blog.find()
    {
         "_id" : ObjectId("5c8e1003c38926f35f6c022e"), "title" : "My Blog Post", "content" : "Here's my blog post.", "date" : ISODate("2019-03-17T09:12:51.098Z") }

## 读取 ##

find会返回集合里面所有的文档。如果只是想查看一个文档，使用findOne

> db.blog.findOne()
    {
    	"_id" : ObjectId("5c8e1003c38926f35f6c022e"),
    	"title" : "My Blog Post",
    	"content" : "Here's my blog post.",
    	"date" : ISODate("2019-03-17T09:12:51.098Z")
    }

## 更新 ##

1、增加comments键

> post.comments=[]
    [ ]

2、替换更新文档

> db.blog.update({
        title:"My Blog Post"}, post)
    WriteResult({
         "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })

## 删除 ##

remove用来从数据库中永久的删除文档：删除符合条件的文档

> db.blog.remove({"title" : "My Blog Post"});
    WriteResult({ "nRemoved" : 2 })
    > db.date.remove({});  //删除所有

# shell 帮助文档 #

>help
    >

*  输入函数的时候不要()，就可以看到JS源代码了

> db.foo.update
    function (query, obj, upsert, multi) {
        
        var parsed = this._parseUpdate(query, obj, upsert, multi);
        var query = parsed.query;
        var obj = parsed.obj;
        var upsert = parsed.upsert;
        var multi = parsed.multi;
        var wc = parsed.wc;
        var collation = parsed.collation;
        var arrayFilters = parsed.arrayFilters;
    
        var result = undefined;
        var startTime =
            (typeof(_verboseShell) === 'undefined' || !_verboseShell) ? 0 : new Date().getTime();
    
        if (this.getMongo().writeMode() != "legacy") {
        
            var bulk = this.initializeOrderedBulkOp();
            var updateOp = bulk.find(query);
    
            if (upsert) {
        
                updateOp = updateOp.upsert();
            }
    
            if (collation) {
        
                updateOp.collation(collation);
            }
    
            if (arrayFilters) {
        
                updateOp.arrayFilters(arrayFilters);
            }
    
            if (multi) {
        
                updateOp.update(obj);
            } else {
        
                updateOp.updateOne(obj);
            }
    
            try {
        
                result = bulk.execute(wc).toSingleResult();
            } catch (ex) {
        
                if (ex instanceof BulkWriteError) {
        
                    result = ex.toSingleResult();
                } else if (ex instanceof WriteCommandError) {
        
                    result = ex;
                } else {
        
                    // Other exceptions thrown
                    throw ex;
                }
            }
        } else {
        
            if (collation) {
        
                throw new Error("collation requires use of write commands");
            }
    
            if (arrayFilters) {
        
                throw new Error("arrayFilters requires use of write commands");
            }
    
            this.getMongo().update(this._fullName, query, obj, upsert, multi);
    
            // Enforce write concern, if required
            if (wc) {
        
                result = this.runCommand("getLastError", wc instanceof WriteConcern ? wc.toJSON() : wc);
            }
        }
    
        this._printExtraInfo("Updated", startTime);
        return result;
    }

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