@preethi.minti Your app works online and offline. So my strong reference is use Couchbase Base Lite for Mobile Applicaitons because it has a power full tool Couchbase Sync Gateway
Couchbase base offers us to convert our existing db to coubase here are some of the useful links
http://blog.couchbase.com/2016/february/moving-from-oracle-to-couchbase
http://blog.couchbase.com/2016/february/moving-from-mongodb-to-couchbase-server