Remove:

remove the wand with the name of "Doom Bringer" from our wandscollection.

db.wands.remove({name: "Doom Bringer"})>> WriteResult({'ngRemoved': 1})

 

When we removed the "Doom Bringer" wand, we noticed that it had a power of "Death", and we don't want any wands like that in our database. To be safe, let's remove any wands containing that in their powers.

db.wands.remove({name: "Doom Bringer", powers: "Death"})

 

Update:

Write the command to update the wand with a name of "Devotion Shift" and set the price to 5.99.

db.wands.update({name: "Devotion Shift"},{"$set": {price: 5.99}});

 

Update all the document: "multi"

Increase level_required by 2, apply to all the documents match {powers: "Fire"}:

db.wands.update(  {powers: "Fire"},  {
    "$inc":{level_required: 2}},  {
    "multi": true})

 

Create new document if there is no existing one: "upsert"

db.logs.update(  {name: "Dream Bender"},  {
    "$inc": {count: 1}},  {
    "upsert": true})