Mongdb 101 Part 1

Create new collection:

db.users.insert({username:"beckerbao"})

Update or add new element (reference link: http://docs.mongodb.org/manual/core/write-operations-introduction/)

db.users.update({username:"beckerbao"},{$set,{country:"vietnam"}})

Add 1 more item to array:

1. Create country with array type
   
   

   db.users.update({username:"beckerbao"},{$set,{country:["vietnam"]}})

2. Add new item
   
   

   db.users.update({username:"beckerbao"},{$addToSet,{country:["usa"]}})

Delete an item in collection:

db.users.update({username:"beckerbao"},{$unset,{country:1}})