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How to get the last N Records in MongoDB?
If you use the auto created _id field it has a date embedded in it so you can use that to order by That will return back all your documents sorted from oldest to newest. You can also use a Natural Order mentioned above
How does db.collection.find ( ) work in Mongo?
Executing db.collection.find() in the mongo shell automatically iterates the cursor to display up to the first 20 documents. Type it to continue iteration. To access the returned documents with a driver, use the appropriate cursor handling mechanism for the driver language.
How to specify a field in a MongoDB document?
For fields in an embedded documents, you can specify the field using either: nested form; e.g. { field: { nestedfield: } } ( Starting in MongoDB 4.4) The _id field is included in the returned documents by default unless you explicitly specify _id: 0 in the projection to suppress the field.
Which is the only field you can exclude in MongoDB?
In projections that explicitly include fields, the _id field is the only field that you can explicitly exclude. In projections that explicitly excludes fields, the _id field is the only field that you can explicitly include; however, the _id field is included by default.
Which is the correct query for missing fields in MongoDB?
The { item : { $exists: false } } query matches documents that do not contain the item field: The query only returns the document that does not contain the item field. Starting in MongoDB 4.2, users can no longer use the query filter $type: 0 as a synonym for $exists:false.
When to perform an ordered insert in MongoDB?
If true, perform an ordered insert of the documents in the array, and if an error occurs with one of documents, MongoDB will return without processing the remaining documents in the array. If false, perform an unordered insert, and if an error occurs with one of documents, continue processing the remaining documents in the array.
How to find a null document in MongoDB?
The { item : null } query matches documents that either contain the item field whose value is null or that do not contain the item field. db.inventory.find ({ item: null }) The query returns both documents in the collection.