Video Transcript (English)

Hi, folks. In this video, you’ll learn how to delete documents in MongoDB by using deleteOne() and deleteMany(). Let’s jump right into it!

Imagine that you're working with a database that contains information about various podcasts. There's a single document for each podcast that gets added to the collection, which is called `podcasts`. But there’s a problem.

At some point, a duplicate document for a podcast was inserted accidentally.

We need to delete the duplicate. To achieve this, we’ll first use `find` to determine which document to delete. Then we’ll use the `deleteOne() method`.

Furthermore, your manager asks you to remove all podcasts with a category of “crime”.

First, we provide a filter document to the `find()` method that contains the `uploaded` date of the duplicate document, which was provided to us by our manager. The date we were given is April 28, 2020. In the shell, we’ll use the `ISODate()` wrapper to specify the date.

Running this command returns the duplicate document. Now we’ll use the `_id` value to write the `deleteOne()` command.

The `deleteOne()` method accepts a filter document and an options object; however, we won’t be using the options object in this example. In the filter document, we’ll put the `_id` value of the duplicate.

After running this command, we receive a message that our command was acknowledged and that one document was deleted. Perfect!

Now that you know how to delete one document, let's go over the process for deleting more than one.

We’ll delete all podcasts that have a category of “crime.”

First, we’ll run a `find` for podcasts in the crime category, which returns three results.

Now we’ll use `deleteMany()` to delete all three podcasts.

We’ll pass in a filter document that contains the field “category” and a value of “crime”. Like `deleteOne`, the `deleteMany()` method accepts an options object, but it’s not required for this example.

When we run this command, we get output showing that 3 documents were deleted, which is what we want.

Now let’s recap what you learned in this video.

To delete one document, use `deleteOne()` by passing in a filter document and an options object if needed. Note that the options object is not required for this query.

To delete more than one document, use `deleteMany(), which also accepts a filter and an options object.

Congratulations on working with the `deleteOne()` and `deleteMany()` methods in MongoDB!