Mongodb (2) Create a database, delete a database, create a collection, delete a collection, display the contents of a document

Show all Databases list: Show DBS

> show dbslocal   0. 078GBrunoob  0. 078GB

Show current database: DB

> Dbrunoob

Show All collections: Show Collections--Show all collections of the current database

> Show Collectionscol_1col_2runoobsystem.indexes

CREATE DATABASE: Use database_name-Create a database named database_name and switch to the database you created, or you can switch directly to a database that already exists

> Use mydbswitched to db mydb> dbmydb>show dbs   #新创建的不会显示 because there is no data inside
Local   0.078GB
Runoob  0.078GB
> db.movie.insert ({"Name": "Tutorials Yiibai"})   #向当前数据库插入一个集合movie (if automatic creation is not present) and inserts a document into the collection
Writeresult ({"ninserted": 1})
> Show DBS
Local   0.078GB
MyDB    0.078GB
Runoob 0.078GB
> Show Collections   #显示当前数据库中的集合
Movie
System.indexes
> Db.movie.find ()    #展示集合中的内容
{"_id": ObjectId ("578de9095dadb19a13cd9062"), "name": "Tutorials Yiibai"}
>

Delete database: Db.dropdatabase ()

> show dbslocal   0.078GBmydb    0.078GBrunoob  0.078GB> dbmydb>"  dropped""mydb""OK" : 1 }> show dbslocal   0.078GBrunoob  0.078GB

Create a collection:db. CreateCollection(name, options)

Name is the name of the collection, options (optional) specifies the memory size and index

>show dbslocal 0.078GBrunoob 0.078GB>DB #上步删除之后还会显示mydb>Use Runoob #切换数据库switched to DB Runoob>Dbrunoob>Show Collections #显示当前的集合col_1col_2runoobsystem. indexes
> db.createcollection ("mycollection") #创建集合
{"OK": 1}
> Show Collections #显示所有的集合
Col_1
   col_2
     mycollection
      Runoob
       system.indexes
>

Important options for creating collections: CreateCollection ()

> Db.createcollection ("MyCol", {capped:true, autoindexid:true, size:6142800, max:10000 } ){ "OK": 1 }>Show Collectionscol_1col_2mycolmycollectionrunoobsystem.indexes> Db.yiibai.insert ({"name":"Yiibai"}) Writeresult ({"ninserted": 1 })>Show Collectionscol_1col_2mycolmycollectionrunoobsystem.indexesyiibai>

Delete collection:db. Collection_name. Drop()

> show Collectionscol_1col_2mycolmycollectionrunoobsystem.indexesyiibai> db.mycollection.drop ( True> Db.yiibai.drop ()  # successfully deleted the already existing collection true> db.mycol.drop () True > show collectionscol_1col_2runoobsystem.indexes# Delete nonexistent collection, error false 

Use the Find command to view the contents of the document: Db.collection_name.find ()

>Dbrunoob>Db.rundb.runCommand (Db.runoob>Db.runoob.find () {"_id": ObjectId ("578dc96c5dadb19a13cd905e"),"Word":"Hello","Chinese":"It's a Nice day today!","中文版":"Today the weather is well!" }>Show Collectionscol_1col_2runoobsystem.indexes>Db.col_2.find () {"_id": ObjectId ("578dd2b95dadb19a13cd9061"),"name":"Xiaohua"," Age":" the" }>Db.col_1.find () {"_id": ObjectId ("578dd2255dadb19a13cd905f"),"name":"Chenugnag" }{ "_id": ObjectId ("578dd23a5dadb19a13cd9060"),"name":"xiaoming"," Age":" -" }>

Mongodb (2) Create a database, delete a database, create a collection, delete a collection, display the contents of a document