how to query on multiple collection from mongodb using nifi?

[#1]

Hi Friends,

   I have a scenario, need to import big documents(.xlsx), then converting to csv and then to json  , then using putMongo using Nifi.

Now I want to query on these collections(2),  like any select sql query with where clause ...

the SQL query:

select t1.X, t1.Y_DT,t1.Z,t1.adj,t1.bjc,t1.jbc,t1.mnk,t2.adj1,t2.bjc1,t2.jbc1,t2.mnk1 from inpt1 t1, input2 t2 where t1.X = t2.X AND t1.Y_DT=t2.Y_DT AND t1.Z = t2.Z;

A similar mongodb query needed…, 

How to do using Nifi ? something like above.

If there is any sample workflow, plz point to me to that.