[{_id:1,emp:"A",name:"nameA",age:23},{_id:2,emp:"B",name:"nameB",age:54},{_id:3,emp:"C",name:"nameC",age:45}]

db.collection.update({emp:"E"},{$set:{name:"nameE",age:23},"$setOnInsert":{_id:5,emp:"E"}},{upsert:true})