Some basics of Mongo DB !!!!!!!!!

What is Mongo DB?

• A Non-relational database.
• Document oriented database.

Mongo Data Model (from http://www.mongodb.org/display/DOCS/Introduction)

• A Mongo system holds a set of databases
• A database holds a set of collections
• A collection holds a set of documents
• A document is a set of fields
• A field is a key-value pair
• A key is a name (string)
• A value is a
  • basic type like string, integer, float, timestamp, binary, etc.,
  • a document, or
  • an array of values

How to Install ?

1. Download from http://www.mongodb.org/downloads
2. Extract it to c:/mongodb
3. Go to c:/mongodb/bin, there you can see mongo.exe (client) and mongod.exe (database server)
4. Create the folders to store the database. Default is c:/data/db
5. After doing these steps, go to command prompt and execute mongod first
6. Then execute mongo.exe.
7. Then you can start playing with commands, try db.version()  

Playing with Mongo DB Commands

• db.help() - gets all the command
• db.stats() - gets database details such as DB name, no of collections, data size, indexes & etc. 
• db.test (test is the collection name) - Create to a collection
• db.getCollectionNames() - the names of the collections made.
• use test - switches to the specified collection

Now you are in the "test" collection let's do some CURD operations !!!!!!!

Reading data

db.test.find()

SELECT * FROM tbl_name

db.test.find({gender: f})

SELECT * FROM tbl_nameWHERE geneder ='f'

db.test.find({gender: {$ne: 'f'}, weight: {$gte: 70}})

SELECT * FROM tbl_name WHERE gender !='f' AND weight >= 70

db.test.find({gender: 'f', $or: [{name: 'jen'}, {name: 'ann'}, {weight: {$lt: 50}}]})

SELECT * FROM name WHERE gender='f' AND name='jen' OR name='ann' AND weight < 50

Insert Data

db.test.insert({name: 'ann', dob: new Date(1985,2,13), city: 'london'});

Remove Data

db.test.remove()

DELETE FROM tbl_name;

db.test.remove({city:'london'})

DELETE FROM tbl_name WHERE city='london';

Update Data

db.test.update({id: 1202}, {$set: {name: 'ann mary' }})

UPDATE tbl_name SET name='ann mary' WHERE id=1202

All the CURD features looks similar so far but here are some strange features;

db.test.update({name: 'ann'}, {$inc: {count: +2 }})
Count is increased by 2 in order to decrease use minus(-)

db.test.update({name: 'ann'}, {$push: {age: 23 }})
New field called age is appended

What is an UPSERT ??????

It UPDATES if the document is already there if not it inserts a document but in order to do that third parameter has to be specified.

db.test.update({page: 'unicorns'}, {$inc: {hits: 1}}, true); 

Multiple Updates !!

Only the first matching record is updated unless it is told to do multiple updates. It is done by specifying the fourth parameter.

db.test.update({}, {$set: {activate: true }}, false, true);