MongoDB學習筆記之文檔

#向集合中插入文檔有兩種方式(insert、save)

db.col.insert({title: 'MongoDB 教程', 
    description: 'MongoDB 是一個 Nosql 數據庫',
    by: '菜鳥教程',
    url: 'http://www.runoob.com',
    tags: ['mongodb', 'database', 'NoSQL'],
    likes: 100
});

# 也能夠把文檔賦值給變量
document=({title: 'MongoDB 教程', 
    description: 'MongoDB 是一個 Nosql 數據庫',
    by: '菜鳥教程',
    url: 'http://www.runoob.com',
    tags: ['mongodb', 'database', 'NoSQL'],
    likes: 100
});

db.col.insert(document)

　

#查詢集合中的文檔，經過find
db.col.find();
{ "_id" : ObjectId("5d020b62f99940c1effaa307"), "title" : "MongoDB 教程", "description" : "MongoDB 是一個 Nosql 數據庫", "by" : "菜鳥教程", "url" : "http://www.runoob.com", "tags" : [ "mongodb", "database", "NoSQL" ], "likes" : 100 }
{ "_id" : ObjectId("5d020b80f99940c1effaa308"), "title" : "MongoDB 教程", "description" : "MongoDB 是一個 Nosql 數據庫", "by" : "菜鳥教程", "url" : "http://www.runoob.com", "tags" : [ "mongodb", "database", "NoSQL" ], "likes" : 100 }
{ "_id" : ObjectId("5d020b81f99940c1effaa309"), "title" : "MongoDB 教程", "description" : "MongoDB 是一個 Nosql 數據庫", "by" : "菜鳥教程", "url" : "http://www.runoob.com", "tags" : [ "mongodb", "database", "NoSQL" ], "likes" : 100 }
{ "_id" : ObjectId("5d020b82f99940c1effaa30a"), "title" : "MongoDB 教程", "description" : "MongoDB 是一個 Nosql 數據庫", "by" : "菜鳥教程", "url" : "http://www.runoob.com", "tags" : [ "mongodb", "database", "NoSQL" ], "likes" : 100 }
{ "_id" : ObjectId("5d020b83f99940c1effaa30b"), "title" : "MongoDB 教程", "description" : "MongoDB 是一個 Nosql 數據庫", "by" : "菜鳥教程", "url" : "http://www.runoob.com", "tags" : [ "mongodb", "database", "NoSQL" ], "likes" : 100 }
{ "_id" : ObjectId("5d020b84f99940c1effaa30c"), "title" : "MongoDB 教程", "description" : "MongoDB 是一個 Nosql 數據庫", "by" : "菜鳥教程", "url" : "http://www.runoob.com", "tags" : [ "mongodb", "database", "NoSQL" ], "likes" : 100 }
{ "_id" : ObjectId("5d020b84f99940c1effaa30d"), "title" : "MongoDB 教程", "description" : "MongoDB 是一個 Nosql 數據庫", "by" : "菜鳥教程", "url" : "http://www.runoob.com", "tags" : [ "mongodb", "database", "NoSQL" ], "likes" : 100 }
{ "_id" : ObjectId("5d020b85f99940c1effaa30e"), "title" : "MongoDB 教程", "description" : "MongoDB 是一個 Nosql 數據庫", "by" : "菜鳥教程", "url" : "http://www.runoob.com", "tags" : [ "mongodb", "database", "NoSQL" ], "likes" : 100 }

比較insert和save的區別：

其實insert和save在不指定_id的時候效果是同樣的,若是指定了_id字段,那麼save就是更新當前文檔信息

{ "_id" : ObjectId("5d020beff99940c1effaa316"), "title" : "MongoDB 教程", "description" : "MongoDB 是一個 Nosql 數據庫", "by" : "菜鳥教程", "url" : "http://www.runoob.com", "tags" : [ "mongodb", "database", "NoSQL" ], "likes" : 100 }

#利用save方法指定_id
db.col.save({
        "_id":"5d020beff99940c1effaa316",
        "title" : "java 教程",
        "description" : "java是一個跨平臺的編程語言",
        "by" : "菜鳥教程",
        "url" : "http://www.runoob.com",
        "tags" : [
                "java8",
                "註解",
                "反射",
                "網絡編程",
                "epoll 事件驅動",
                "多路複用",
                "聲明式API"
        ],
        "likes" : 100
});

#結果以下
{ "_id" : "5d020beff99940c1effaa316", "title" : "java 教程", "description" : "java是一個跨平臺的編程語言", "by" : " 菜鳥教程", "url" : "http://www.runoob.com", "tags" : [ "java8", "註解", "反射", "網絡編程", "epoll 事件驅動", "多路 複用", "聲明式API" ], "likes" : 100 }

#save和update的區別,save通常是經過_id字段匹配原先的文檔後用新的文檔替換掉原先的文檔，而upate是根據條件對局部進行更新

#update的語法以下：
db.collection.update(
   <query>,
   <update>,
   {
     upsert: <boolean>,
     multi: <boolean>,
     writeConcern: <document>
   }
)

query : update的查詢條件，相似sql update查詢內where後面的。

update : update的對象和一些更新的操做符（如$,$inc...）等，也能夠理解爲sql update查詢內set後面的

upsert : 可選，這個參數的意思是，若是不存在update的記錄，是否插入objNew,true爲插入，默認是false，不插入。

multi : 可選，mongodb 默認是false,只更新找到的第一條記錄，若是這個參數爲true,就把按條件查出來多條記錄所有更新。

writeConcern :可選，拋出異常的級別