Getting Started with Mongo DB

Installation & Startup:

Download MongoDB installer for windows platform from http://www.mongodb.org/downloads and run. This simply extracts the binaries to your program files.

#Create DBPATH and log libraries:

Allocate a folder in your system that can be used for holding the mongo databases and also allocate a log file.

Ex – Allocated “C:\mongo\data\db” for databases and “C:\mongo\logs\mongo.log” as a log file.

#Starting the mongo database

Below are different ways of starting the mongodb:

1.    From the command prompt

Execute the mongod.exe present in the bin folder to start the database.

On command prompt à mongod --dbpath c:\mongo\data\db

There are other options that can also be specified alongwith dbpath. If dbpath is not provided, it looks for c:\data\db folder and gives error if not found.

To shutdown, press CTRL+C

2.    Starting with a config file

You can create a configuration file to define settings for the MongoDB server like the dbpath,logpath etc. Below is a sample file :

(This is a older format, for 2.6 version a new format is introduced. Older format is supported for backward compatibility)

#This is an example config file for MongoDB

dbpath = C:\Mongo\data\db

port = 27017

logpath = C:\Mongo\logs\mongo.log

Now you can use the below command –

C:\Program Files\MongoDB 2.6 Standard\bin>mongod --config mongo.conf

2014-04-15T10:27:18.883+0530 log file "C:\Mongo\logs\mongo.log" exists; moved to

"C:\Mongo\logs\mongo.log.2014-04-15T04-57-18".

As we haven’t specified “logappend” option in the config file, it allocates new file everytime you start the db. You can check the log file if you are getting errors while connecting to the db

To shutdown, use command “mongod –shutdown”

3.    Installing as Windows service:

Start the command prompt as administrator

You can use the below command to create the service, edit the same as per your settings:

sc create MongoDB binPath= "\"C:\Program Files\MongoDB 2.6 Standard\bin\mongod.exe\" --service --config=\"C:\Program Files\MongoDB 2.6 Standard\bin\mongo.conf\"" DisplayName= "MongoDB 2.6 Standard"

Please note this is a single line of command

You can now simply start/stop the service to start/shutdown the mongo database.

Using Mongo command shell:

Run Mongo.exe from \bin folder and you will see the below:

MongoDB shell version: 2.6.0

connecting to: test      //This is the Default database

Welcome to the MongoDB shell.

For interactive help, type "help".

For more comprehensive documentation, see

http://docs.mongodb.org/

Questions? Try the support group

http://groups.google.com/group/mongodb-user

Some basic commands to get you started

> show dbs                  // show databases

admin  (empty)
local  0.078GB

> use names               // switch to a particular database/creates one if it does not exist

switched to db names

> db.mynames.insert({name: 'shraddha', email: 'shraddha@gmail'})           // Inserting document
WriteResult({ "nInserted" : 1 })

//Note that , ‘db’ points to the current database in use. Here, Collection “mynames” is automatically created when you insert a document

> show dbs

admin  (empty)
local  0.078GB
names  0.078GB

> db.mynames.find()               //query the db, select operation

{ "_id" : ObjectId("534cbfd03dfb3fbd86d8029d"), "name" : "shraddha", "email" : "shraddha@gmail" }

//One more way of inserting……

> a={"name":"test3","email":"test3.other"}

{ "name" : "test3", "email" : "test3.other" }

> b={"name":"test4",email:"test4.other"}

{ "name" : "test4", "email" : "test4.other" }

> db.othernames.insert(a)

WriteResult({ "nInserted" : 1 })

> db.othernames.insert(b)

WriteResult({ "nInserted" : 1 })

> db.othernames.insert(c)

2014-04-15T19:40:24.798+0530 ReferenceError: c is not defined

//…In all the above inserts, the “_id” which has the unique key is auto-generated..

 

> coll=db.mynames

names.mynames

> coll.find()

{ "_id" : ObjectId("534cbfd03dfb3fbd86d8029d"), "name" : "shraddha", "email" : "shraddha@gmail" }
{ "_id" : ObjectId("534d3b89f4d4b90697c205d6"), "name" : "test1", "email" : "test1.helical" }

> coll=db.othernames

names.othernames

> coll.find()

{ "_id" : ObjectId("534d3dc3f4d4b90697c205d7"), "name" : "test3", "email" : "test3.other" }
{ "_id" : ObjectId("534d3dcdf4d4b90697c205d8"), "name" : "test4", "email" : "test4.other" }

 

> coll.find({name:{$gt:"test3"}})                  //find documents where “name” is >”test3”

{ "_id" : ObjectId("534d3dcdf4d4b90697c205d8"), "name" : "test4", "email" : "test4.other" }

> coll.find({name:"test3"})

{ "_id" : ObjectId("534d3dc3f4d4b90697c205d7"), "name" : "test3", "email" : "test3.other" }

>

> coll.find({$or:[{name:{$gt:"test3"}},{name:"test3"}]})

{ "_id" : ObjectId("534d3dc3f4d4b90697c205d7"), "name" : "test3", "email" : "test3.other" }
{ "_id" : ObjectId("534d3dcdf4d4b90697c205d8"), "name" : "test4", "email" : "test4.other" }

> coll.find({$or:[{name:{$gt:"test3"}},{name:"test0"}]})

{ "_id" : ObjectId("534d3dcdf4d4b90697c205d8"), "name" : "test4", "email" : "test4.other" }

>
 
//Example - Manually inserting ObjectID field (key value)
 
> coll=db.testobjs

names.testobjs

> coll.insert({_id:1,fld1:"abc",fld2:123})

WriteResult({ "nInserted" : 1 })

> coll.insert({_id:2,fld1:"cde",fld2:345})

WriteResult({ "nInserted" : 1 })

> coll.insert({_id:2,fld1:"cde",fld2:345})       //trying to insert duplicate value in _id

WriteResult({
"Inserted" : 0,
"writeError" : {
"code" : 11000,
"errmsg" : "insertDocument :: caused by :: 11000 E11000 duplicate key error index: names.testobjs.$_id_  dup key: { : 2.0 }"}}

> coll.find()

{ "_id" : 1, "fld1" : "abc", "fld2" : 123 }
{ "_id" : 2, "fld1" : "cde", "fld2" : 345 }

>
 

Importing a csv file into mongodb:

Alter the below command as per your requirement and execute:

C:\Program Files\MongoDB 2.6 Standard\bin>mongoimport --db northwind --collection orders --type csv --file C:\Shraddha\Official\MongoDB\northwind-mongo-master\orders.csv --headerline

connected to: 127.0.0.1
2014-04-17T18:24:22.603+0530 check 9 831
2014-04-17T18:24:22.604+0530 imported 830 objects

 

Options used –

–db : name of the database
–collection : orders
–type : type of input file (we can also import tsv, JSON)
–file : path of the input file
–headerline : signifies that the first line in the csv file is column names

Shraddha Tambe

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