Mongodb（3）插入文档，更新文档，删除文档

insert() 方法

要插入数据到 MongoDB 集合，需要使用 MongoDB 的  insert() 或 save() 方法。

插入文档：db.COLLECTION_NAME.insert(document)

 > show collections
 col_1
 col_2
 runoob
 system.indexes
 > db.mycol.insert({"title":"MongoDb overview"})#如果之前该集合不存在，则重新创建集合
 WriteResult({ "nInserted" : 1 })#成功插入文档
 > show collections
 col_1
 col_2
 mycol
 runoob
 system.indexes
 > db.mycol.find()
 { "_id" : ObjectId("57906a93b2dade9538e2ac1e"), "title" : "MongoDb overview" }

MongoDB的 update() 和 save() 方法用于更新文档的集合。 update()方法更新现有的文档值，而替换现有的文档通过的文件中 save() 方法。

MongoDB Update() 方法

update()方法更新现有文档值。

更新文档：db.COLLECTION_NAME.update(SELECTIOIN_CRITERIA, UPDATED_DATA)

> db.mycol.find()
{ "_id" : ObjectId("57906a93b2dade9538e2ac1e"), "title" : "MongoDb overview" }
{ "_id" : ObjectId("57906dd3b2dade9538e2ac1f"), "title" : "alili MongoDb" }
{ "_id" : ObjectId("57906ddfb2dade9538e2ac20"), "title" : "mongodb" }
> db.mycol.update({"name":"no name"})#做了个测试
2016-07-21T14:39:29.359+0800 E QUERY    Error: need an object
    at Error (<anonymous>)
    at DBCollection._parseUpdate (src/mongo/shell/collection.js:400:21)
    at DBCollection.update (src/mongo/shell/collection.js:432:23)
    at (shell):1:10 at src/mongo/shell/collection.js:400
> db.mycol.update({"title":"mongodb"},{$set:{"title":"change mongodb"}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.mycol.find()
{ "_id" : ObjectId("57906a93b2dade9538e2ac1e"), "title" : "MongoDb overview" }
{ "_id" : ObjectId("57906dd3b2dade9538e2ac1f"), "title" : "alili MongoDb" }
{ "_id" : ObjectId("57906ddfb2dade9538e2ac20"), "title" : "change mongodb" }
> db.mycol.update({"title" : "change mongodb"},{$set:{"name":"no name"}})#然后又做了一次改变，是在后面追加的
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.mycol.find()
{ "_id" : ObjectId("57906a93b2dade9538e2ac1e"), "title" : "MongoDb overview" }
{ "_id" : ObjectId("57906dd3b2dade9538e2ac1f"), "title" : "alili MongoDb" }
{ "_id" : ObjectId("57906ddfb2dade9538e2ac20"), "title" : "change mongodb", "name" : "no name" }

MongoDB Save() 方法

save() 方法替换现有的文档和通过新的文档 save() 方法

语法

MongoDB 的 save() 方法的基本语法如下：

替换现有文档：db.COLLECTION_NAME.save({_id:ObjectId(),NEW_DATA})

> db.mycol.find()
{ "_id" : ObjectId("57906a93b2dade9538e2ac1e"), "title" : "MongoDb overview" }
{ "_id" : ObjectId("57906dd3b2dade9538e2ac1f"), "title" : "alili MongoDb" }
{ "_id" : ObjectId("57906ddfb2dade9538e2ac20"), "title" : "change mongodb", "name" : "no name" }
> db.mycol.save({"_id" : ObjectId("57906a93b2dade9538e2ac1e"),"name":"mongodb","by":"save"})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.mycol.find()
{ "_id" : ObjectId("57906a93b2dade9538e2ac1e"), "name" : "mongodb", "by" : "save" }
{ "_id" : ObjectId("57906dd3b2dade9538e2ac1f"), "title" : "alili MongoDb" }
{ "_id" : ObjectId("57906ddfb2dade9538e2ac20"), "title" : "change mongodb", "name" : "no name" }
> 

MongoDB的 remove() 方法用于从集合中删除文档。remove() 方法接受两个参数。第一个是删除criteria ，第二是justOne标志：

1. deletion criteria :（可选）删除标准，根据文件将被删除。

2. justOne : （可选）如果设置为true或1，然后只删除一个文件。

删除文档：db.COLLECTION_NAME.remove(DELLETION_CRITTERIA)

> db.mycol.find()
{ "_id" : ObjectId("57906a93b2dade9538e2ac1e"), "name" : "mongodb", "by" : "save" }
{ "_id" : ObjectId("57906dd3b2dade9538e2ac1f"), "title" : "alili MongoDb" }
{ "_id" : ObjectId("57906ddfb2dade9538e2ac20"), "title" : "change mongodb", "name" : "no name" }
> db.mycol.remove({"title":"alili MongoDb"})
WriteResult({ "nRemoved" : 1 })
> db.mycol.find()
{ "_id" : ObjectId("57906a93b2dade9538e2ac1e"), "name" : "mongodb", "by" : "save" }
{ "_id" : ObjectId("57906ddfb2dade9538e2ac20"), "title" : "change mongodb", "name" : "no name" }
> db.mycol.insert({"name":""})
WriteResult({ "nInserted" : 1 })
> db.mycol.insert({"name":""})
WriteResult({ "nInserted" : 1 })
> db.mycol.find()
{ "_id" : ObjectId("57906a93b2dade9538e2ac1e"), "name" : "mongodb", "by" : "save" }
{ "_id" : ObjectId("57906ddfb2dade9538e2ac20"), "title" : "change mongodb", "name" : "no name" }
{ "_id" : ObjectId("579077d9b2dade9538e2ac21"), "name" : "" }
{ "_id" : ObjectId("579077dbb2dade9538e2ac22"), "name" : "" }
> db.mycol.remove({"name":""})#相同的都会删去的
WriteResult({ "nRemoved" : 2 })
> db.mycol.find()
{ "_id" : ObjectId("57906a93b2dade9538e2ac1e"), "name" : "mongodb", "by" : "save" }
{ "_id" : ObjectId("57906ddfb2dade9538e2ac20"), "title" : "change mongodb", "name" : "no name" }
> 

只删除一个：db.COLLECTION_NAME.remove(DELETION_CRITERIA,1)

> db.mycol.find()
{ "_id" : ObjectId("57906a93b2dade9538e2ac1e"), "name" : "mongodb", "by" : "save" }
{ "_id" : ObjectId("57906ddfb2dade9538e2ac20"), "title" : "change mongodb", "name" : "no name" }
{ "_id" : ObjectId("5790789fb2dade9538e2ac23"), "age" : "" }
{ "_id" : ObjectId("579078a1b2dade9538e2ac24"), "age" : "" }
{ "_id" : ObjectId("579078a4b2dade9538e2ac25"), "age" : "" }
> db.mycol.remove({"age":""},1)
WriteResult({ "nRemoved" : 1 })
> db.mycol.find()
{ "_id" : ObjectId("57906a93b2dade9538e2ac1e"), "name" : "mongodb", "by" : "save" }
{ "_id" : ObjectId("57906ddfb2dade9538e2ac20"), "title" : "change mongodb", "name" : "no name" }
{ "_id" : ObjectId("579078a1b2dade9538e2ac24"), "age" : "" }
{ "_id" : ObjectId("579078a4b2dade9538e2ac25"), "age" : "" }
> 

删除集合的所有的内容：db.COLLECTION_NAME.remove({})

> db.mycol.find()
{ "_id" : ObjectId("57906a93b2dade9538e2ac1e"), "name" : "mongodb", "by" : "save" }
{ "_id" : ObjectId("57906ddfb2dade9538e2ac20"), "title" : "change mongodb", "name" : "no name" }
{ "_id" : ObjectId("579078a1b2dade9538e2ac24"), "age" : "" }
{ "_id" : ObjectId("579078a4b2dade9538e2ac25"), "age" : "" }
> db.mycol.remove()#抛出了异常，去搜了下
2016-07-21T15:33:45.122+0800 E QUERY    Error: remove needs a query
    at Error (<anonymous>)
    at DBCollection._parseRemove (src/mongo/shell/collection.js:305:32)
    at DBCollection.remove (src/mongo/shell/collection.js:328:23)
    at (shell):1:10 at src/mongo/shell/collection.js:305
> db.mycol.remove({})
WriteResult({ "nRemoved" : 4 })
> db.mycol.find()
>