MongoDB - Querying Nested Documents

            
 

            

        

          

          
          

          

              

                  
              

          










Create a collection with a nested document as shown below


 
  db.nested.insert({name:"satish",cat1:{eng:40,phy:30,chem:20}});
  db.nested.insert({name:"mathew",cat1:{eng:90,phy:95,chem:80}});





 








Display the english marks for all students


 
  db.nested.find({},{"cat1.eng":1})





 







Display the cat1 marks for student by name mathew 


 
  db.nested.find({name:"mathew"},{name:1,"cat1.eng":1,_id:0});





 







Find the sum of all the english marks scored in cat1


 
  db.nested.aggregate({$project:{"cat1.eng":1}},{$group:{_id:"cat1.eng",total_marks:{$sum:"$cat1.eng"}}});





 







Find the average of all the english marks scored in cat1


 
  db.nested.aggregate({$project:{"cat1.eng":1}},{$group:{_id:"cat1.eng",total_marks:{$avg:"$cat1.eng"}}});