MongoDB- Advanced Operations

MongoDB -Advanced Operations

limit() To limit the records in MongoDB, you need to use limit() method
>db.COLLECTION_NAME.find().limit(NUMBER)

Skip() used to skip the number of documents.
>db.COLLECTION_NAME.find().limit(NUMBER).skip(NUMBER)

sort()  specify sorting order. 1 is used for ascending order while -1 is used for descending order.
>db.COLLECTION_NAME.find().sort({KEY:1})

aggregate() aggregation in MongoDB, you should use aggregate() method.
>db.COLLECTION_NAME.aggregate(AGGREGATE_OPERATION)
AGGREGATE_OPERATION = $sum, $avg, $min, $max, $push, $addToSet, $first, $last

db.collection.save()
Updates an existing document or inserts a new document, depending on its document parameter.
db.products.save( { item: "book", qty: 40 } )

help() uses to guide you how to do things in MongoDB.
 db.help()                    help on db methods
 db.mycoll.help()             help on collection methods
 sh.help()                    sharding helpers
 rs.help()                    replica set helpers
 help admin                   administrative help
 help connect                 connecting to a db help
 help keys                    key shortcuts
 help misc                    misc things to know
 help mr                      mapreduce

 show dbs                     show database names
 show collections             show collections in current database
 show users                   show users in current database
 show profile                 show most recent system.profile entries time >= 1ms
 show logs                    show the accessible logger names
 show log [name]              prints out the last segment of log in memory, 
 use <db_name>                set current database
 db.foo.find()                list objects in collection foo
 db.foo.find( { a : 1 } )     list objects in foo where a == 1
 it                           result of the last line evaluated; use to further iterate
 DBQuery.shellBatchSize = x   set default number of items to display on shell
 exit                         quit the mongo shell