The latest project that I am working on uses mongoDB as the database. mongoDB is a document-oriented database which is quiet different compare to relational database such as SQL. It stores full document(BSON format which is very similar to JSON) and you will be able to query by sending key-value bases BSON object. For example,

db.products.find({})

returns every document in products collection. but you will be able to send query like.

db.products.find({'kind' : 'apparel'})

This query looks for ‘kind’ attribute and return document where ‘kind’ attribute is ‘apparel’.