Post by mamun11 on May 16, 2024 3:39:37 GMT
collection.aggregate $limit: 10 This example returns only the first 10 documents in the collection. 6. Skip number of output documents. For example, if we want to get the documents from a collection after skipping the first 5, we can use the $skip operator as follows: db.collection.aggregate $skip: 5 This example returns the documents in the collection after skipping the first 5.
7. Unwind The $unwind operator is used to Burkina Faso Email List deconstruct an array field across multiple documents. For example, if we have a collection of documents that represent orders with a products field that is an array of products, and we want to obtain a document for each product in each order, we can use the $unwind operator as follows: db.orders.aggregate $unwind: $products This example generates a copy of each document for each product in the products field.
8. Lookup The $lookup operator is used to perform a join operation between collections and combine related data. For example, if we have a collection of documents that represent orders and a collection of documents that represent customers, and we want to add the customer data corresponding to each order, we can use the $lookup operator as follows: db.orders.aggregate $lookup: from: customers, localField: customerId, foreignField: _id, as: customerData This example combines the data from the customers collection based on the customerId field of each order and adds the corresponding customer data in the customerData field.
7. Unwind The $unwind operator is used to Burkina Faso Email List deconstruct an array field across multiple documents. For example, if we have a collection of documents that represent orders with a products field that is an array of products, and we want to obtain a document for each product in each order, we can use the $unwind operator as follows: db.orders.aggregate $unwind: $products This example generates a copy of each document for each product in the products field.
8. Lookup The $lookup operator is used to perform a join operation between collections and combine related data. For example, if we have a collection of documents that represent orders and a collection of documents that represent customers, and we want to add the customer data corresponding to each order, we can use the $lookup operator as follows: db.orders.aggregate $lookup: from: customers, localField: customerId, foreignField: _id, as: customerData This example combines the data from the customers collection based on the customerId field of each order and adds the corresponding customer data in the customerData field.