Database Management Systems
In MongoDB the $sortByCount aggregation pipeline stage groups incoming documents based on the value of a specified expression, then computes the count of documents in each distinct group.
Each group is output in its own document, which consists of two fields:
_id field containing the distinct grouping value, andcount field containing the number of documents belonging to that grouping.The documents are sorted by count in descending order.
In MongoDB the $count aggregation operator passes a document to the next stage in the aggregation pipeline that contains a count of the number of documents input to the current stage.
In MongoDB the cursor.count() method counts the number of documents referenced by a cursor..
Note that it doesn’t actually perform the query. It simply counts and returns the number of results that would be returned by the query.
The cursor.count() method is a wrapper for the count command.
In MongoDB the db.collection.count() method returns the count of documents that would match a find() query for the collection or view.
The collection part is the name of the collection or view to perform the count operation on.
Note that it doesn’t actually perform a find() operation. It simply counts and returns the number of results that match a query.
In MongoDB the count aggregation command counts the number of documents in a collection or a view.
It returns a document that contains the count as well as the command status.
In MongoDB the db.collection.find() method selects documents in a collection or view and returns a cursor to the selected documents..
The collection part is the name of the collection or view to search.
You can use it to return all documents, just some, or just one document. You can also specify which fields should be returned.
In MongoDB the db.collection.findOne() method returns one document that satisfies the specified query criteria on the collection or view.
The collection part is the name of the collection or view to search.
In MongoDB the db.collection.findOneAndDelete() method deletes a single document, and returns the deleted document.
It deletes the first matching document in the collection that matches the filter. The sort parameter can be used to influence which document is deleted.
The collection part is the name of the collection with which to delete the document from.
In MongoDB the db.collection.deleteOne() method removes a single document from a collection. In other words, it deletes it.
The collection part is the name of the collection with which to remove the document from.