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MongoDB
db.collection.deleteOne(filter)
or
db.collection.deleteMany(filter)
Replace collection with the name of the collection from which you want to delete the document(s), and filter with the criteria to select the document(s) to be deleted.
Here’s an example of how to use the db.collection.deleteOne() method to delete a single document in a collection named “users” in the MongoDB shell:
db.users.deleteOne({ _id: ObjectId("60e5b68f5d65d0f90f8d5dd5") })
In this example, the deleteOne() method deletes the document that matches the specified filter, in this case, a document with the _id field set to ObjectId("60e5b68f5d65d0f90f8d5dd5").
To delete multiple documents, you can use the db.collection.deleteMany() method. The syntax is the same, but it deletes all the documents that match the filter:
db.users.deleteMany({ age: { $gte: 30 } })
In this example, the deleteMany() method deletes all documents in the “users” collection where the “age” field is greater than or equal to 30.
When using these deletion methods, MongoDB returns a DeleteResult object that provides information about the operation, including the number of documents deleted.
It’s important to exercise caution when deleting documents, as the deletion is irreversible, and the data cannot be recovered once deleted. Before performing deletions, ensure that you have appropriate backups or data management strategies in place to prevent unintended data loss.
db.collection.deleteOne({ _id: ObjectId("60e5b68f5d65d0f90f8d5dd5") })
In this example, the deleteOne() method is used to delete a single document from the collection. The filter { _id: ObjectId("60e5b68f5d65d0f90f8d5dd5") } selects the document with the _id field set to ObjectId("60e5b68f5d65d0f90f8d5dd5") for deletion.
To delete multiple documents in a collection, you can use the deleteMany() method. The syntax is similar, but it deletes all the documents that match the filter:
db.collection.deleteMany({ age: { $gte: 30 } })
In this example, the deleteMany() method deletes all documents in the collection where the “age” field is greater than or equal to 30.
When deleting documents in MongoDB collections, you have several options to further customize the deletion behavior. Some commonly used options include:
writeConcern: Specifies the write concern for the delete operation, controlling the acknowledgment level and the number of replicas that must acknowledge the write.collation: Specifies the collation to use for string comparisons during the deletion. This allows you to perform case-insensitive or locale-specific deletions.limit: Specifies the maximum number of documents to delete. By default, if no limit is specified, all matching documents are deleted.
These options can be specified as additional parameters in the deleteOne() or deleteMany() methods.
It’s important to exercise caution when deleting documents, as the deletion is irreversible and permanently removes the data. Before performing deletions, ensure that you have appropriate backups, or implement data management strategies to prevent unintended data loss.
Always verify the deletion operation and its impact before executing it on a production database.
db.collection.remove(query, justOne)
Replace collection with the name of the collection from which you want to delete the document(s), query with the filter to select the document(s) to be deleted, and justOne with a boolean value to indicate whether to delete only the first matching document (true) or all matching documents (false).
Here’s an example of how to use the db.collection.remove() method to delete a document from a collection named “users” in the MongoDB shell:
db.users.remove({ _id: ObjectId("60e5b68f5d65d0f90f8d5dd5") })
In this example, the remove() method deletes the document that matches the specified filter, { _id: ObjectId("60e5b68f5d65d0f90f8d5dd5") }, which selects the document with the _id field set to ObjectId("60e5b68f5d65d0f90f8d5dd5").
If you want to delete multiple documents, you can set justOne to false:
db.users.remove({ age: { $gte: 30 } }, false)
In this example, the remove() method deletes all documents in the “users” collection where the “age” field is greater than or equal to 30.
When using the remove() method, MongoDB returns a WriteResult object that contains information about the deletion, including the number of documents deleted.
Again, please note that the remove() method is deprecated, and it is recommended to use the deleteOne() or deleteMany() methods for document deletions in MongoDB collections.
const result = db.users.deleteOne({ _id: ObjectId("60e5b68f5d65d0f90f8d5dd5") });
if (result.acknowledged && result.deletedCount === 1) {
print("Document deleted successfully!");
} else {
print("Failed to delete document.");
}
In this example, the acknowledged field of the result object is checked to determine if the deletion was acknowledged. The deletedCount field indicates the number of documents deleted, and it should be 1 in the case of deleteOne().
To view all documents within a collection in the MongoDB shell, you can use the find() method with an empty query object {}. Here’s the command to view all documents within a collection named “users”:
db.users.find({})
Executing this command will display all the documents present in the “users” collection. Each document will be displayed with its respective fields and values.
You can also use various query modifiers with the find() method to filter or sort the documents based on specific criteria. For example, you can use find({ age: { $gt: 30 } }) to retrieve documents where the “age” field is greater than 30.
It’s important to note that if the collection contains a large number of documents, it may not be practical to view all the documents at once. In such cases, you can use query modifiers like limit() and skip() to control the number of documents displayed or implement pagination techniques to retrieve documents in smaller batches.
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