The basic DDL for getting started with MongoDB

Objective:

This article mainly records the partial DDL operations of the main MongoDB Collection.

• DB view current database (default test)
  

  > dbtest >

• Show DBS View database names on the current database server
  

  > Show Dbsadmin  (empty) Local  0. 078GBmydb   0. 078GBtest   (empty)  >

• Use DbSchema to switch to a database context named DbSchema
  

  >  Use   to db mydb>

  When the database is created with the name DbSchema not present, the database created with use will not be deleted when the switch to another database is not saved.

• Db.dropdatabase () Delete the database where the current period resides

  >1  }>

• Db.stats () View the status of database
  

  >db.stats () {"db": "MyDB", "Collections":3, "Objects":6, "avgobjsize": the, "datasize":480, "storagesize":24576, "numextents":3, "Indexes":1, "indexsize":8176, "fileSize":67108864, "Nssizemb": -, "datafileversion": {"Major":4, "minor":5}, "Extentfreelist": {"num":2, "totalsize":262144}, "OK":1}>

• Show collections View collections within the current database
  

  > Show Collectionscollectsystem.indexes >

• Db.collection.stats () View the status of a collection
  

  >db.collect.stats () {"ns": "Mydb.collect", "Count" :2, "size":224, "avgobjsize": the, "storagesize":8192, "numextents":1, "nindexes":1, "lastextentsize":8192, "Paddingfactor":1, "systemflags":0, "userflags":1, "totalindexsize":8176, "indexsizes": {"_id_":8176}, "OK":1}>

• Db.createcollection (name,options) Create a collection
  Db.createcollection (name, {capped: <boolean>, Autoindexid: <boolean>, size: <number>, Max <number })
  

  > db.createcollection (... ")     Test ",... {...     Capped:true,...     Autoindexid:true,...      1024x768  1  }>

  Name: Collection of names
  Capped: Whether to enable the collection limit, if you need to set a restriction, the default is not enabled, if you want to turn on the Size,max limit, you need to turn on capped
  Size: Limits the amount of space used by the collection, which is not limited by default
  Max: Limit of maximum number of bars in the collection, defaults to No limit
  AUTOINDEXID: Whether to use _id as the index, by default (TRUE or FALSE)
  Size has a higher priority than max
• Db.yourColl.drop () Delete collection
  

  > db.test. Drop () True >

The basic DDL for getting started with MongoDB