Updating a document involves two mandatory arguments: the filter and the update document arguments. The third (optional) argument is options. The primary shell methods used are either db.collection.updateOne(), which—as the name implies—only updates a single document, or db.collection.updateMany(), which lets you perform updates on all documents matching the filter. The former argument is illustrated in the following diagram:
The filter has exactly the same syntax as the query (that is, the first argument to the db.collection.find() command) discussed previously, so we will not repeat that discussion here. The update usually takes the form of a partial document, containing only the fields that need to be replaced with respect to the original. Finally, options are summarized here:
| Option | Values | Notes |
| upsert | true | false | If set to true, a new document is created if none matches the filter. The default is false. |
| writeConcern | write... |
