#declare db path
./mongodb/bin/mongod --dbpath db
#start mongoDB server
./mongodb/bin/mongo
#show databases and collections
show dbs
#switch to databases
use <database_name>
#list the current db indexes
db.<db_name>.getIndexes()
#drop current index
db.<db_name>.dropIndex("<index?name>")
###Query #Count number of null values in a nested field in database db.<database_name>.find('<field?name>.<nested?field>: null).count() #count users with <nested?field1> more than <nested?field2> in nested field db.<database?name>.find({$where : 'this.<field?name>.<nested?field1> > this.<field?name>.<nested?field2>'}).count()