Update and Delete Operations · MongoDB

Ch 2 · MongoDB CRUD Operations — card 5 of 8.

updateOne, updateMany, deleteOne, and deleteMany modify or remove documents. Each takes a filter first to choose which documents are affected. For updates, a second argument uses operators such as $set to change a field, $inc to add to a number, $unset to remove a field and $push to append to an array. Take care with delete filters: an empty filter matches every document.

Update operators: $set changes fields, $inc increments numbers, $unset removes fields, $push adds to arrays. The first argument is the filter, second is the update.

• $set replaces field values
• $inc adds to numeric fields
• $push appends to arrays
• deleteMany removes all matches