To sort by subdocument, use $sort in MongoDB. Let us create a collection with documents −> db.demo245.insertOne( ...   { ...      "_id": 101, ...      "deatils": [ ...         { "DueDate": new ISODate("2019-01-10"), "Value": 45}, ...         {"DueDate": new ISODate("2019-11-10"), "Value": 34 } ...      ] ...   } ...); { "acknowledged" : true, "insertedId" : 101 } > db.demo245.insertOne( ...   { ...      "_id": 102, ...      "details": [ ...         { "DueDate": new ISODate("2019-12-11"), "Value": 29}, ...         {"DueDate": ... Read More

To coalesce values means to merge them. To merge them into a single array, use $project in MongoDB.Let us create a collection with documents −> db.demo244.insertOne({"Value1":10, "Value2":20}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e4582e31627c0c63e7dba63") } > db.demo244.insertOne({"Value1":20, "Value2":30}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e4582f11627c0c63e7dba64") }Display all documents from a collection with the help of find() method −> db.demo244.find();This will produce the following output −{ "_id" : ObjectId("5e4582e31627c0c63e7dba63"), "Value1" : 10, "Value2" : 20 } { "_id" : ObjectId("5e4582f11627c0c63e7dba64"), "Value1" : 20, "Value2" : 30 }Following is the query to coalesce values from different properties into ... Read More

For this, simply use aggregate() in MongoDB. Let us create a collection with documents −> db.demo243.insertOne({"userId":1, dueDate:new ISODate("2019-01-10")}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e4575f81627c0c63e7dba5f") } > db.demo243.insertOne({"userId":2, dueDate:new ISODate("2019-11-10")}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e4576011627c0c63e7dba60") } > db.demo243.insertOne({"userId":2, dueDate:new ISODate("2020-01-31")}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e4576151627c0c63e7dba61") } > db.demo243.insertOne({"userId":1, dueDate:new ISODate("2010-01-10")}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e45761b1627c0c63e7dba62") }Display all documents from a collection with the help of find() method −> db.demo243.find();This will produce the following output −{ "_id" : ObjectId("5e4575f81627c0c63e7dba5f"), "userId" : 1, "dueDate" : ISODate("2019-01-10T00:00:00Z") } { ... Read More

The easiest way to sort an array in MongoDB, use $sort. Let us create a collection with documents −> db.demo242.insertOne( ... ...   {"details2": ...      [ ...         {"ShipingDate":new ISODate("2019-10-11"), "Price":1400}, ...         {"ShipingDate":new ISODate("2019-10-01"), "Price":1600 } ...      ] ...   } ... ...); {    "acknowledged" : true,    "insertedId" : ObjectId("5e4429229af932883c61ea44") }Display all documents from a collection with the help of find() method −> db.demo242.find();This will produce the following output −{    "_id" : ObjectId("5e4429229af932883c61ea44"), "details2" : [       { "ShipingDate" : ISODate("2019-10-11T00:00:00Z"), "Price" : 1400 ... Read More

To get the maximum marks records, use sort() in descending order along with limit 1. Let us create a collection with documents −> db.demo241.insertOne({"Marks":67}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e441f729af932883c61ea40") } > db.demo241.insertOne({"Marks":89}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e441f769af932883c61ea41") } > db.demo241.insertOne({"Marks":78}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e441f789af932883c61ea42") }Display all documents from a collection with the help of find() method −> db.demo241.find();This will produce the following output −{ "_id" : ObjectId("5e441f729af932883c61ea40"), "Marks" : 67 } { "_id" : ObjectId("5e441f769af932883c61ea41"), "Marks" : 89 } { "_id" : ObjectId("5e441f789af932883c61ea42"), "Marks" : 78 }Following ... Read More

To limit the number of records, use $limit in MongoDB. Let us create a collection with documents −> db.demo240.insertOne({"StudentName":"Chris"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e441d969af932883c61ea3c") } > db.demo240.insertOne({"StudentName":"Bob"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e441d9a9af932883c61ea3d") } > db.demo240.insertOne({"StudentName":"David"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e441d9d9af932883c61ea3e") } > db.demo240.insertOne({"StudentName":"Mike"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e441da19af932883c61ea3f") }Display all documents from a collection with the help of find() method −> db.demo240.find();This will produce the following output −{ "_id" : ObjectId("5e441d969af932883c61ea3c"), "StudentName" : "Chris" } { "_id" : ObjectId("5e441d9a9af932883c61ea3d"), "StudentName" : "Bob" } { ... Read More

To limit the number of records, use $limit in MongoDB. Let us create a collection with documents −> db.demo240.insertOne({"StudentName":"Chris"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e441d969af932883c61ea3c") } > db.demo240.insertOne({"StudentName":"Bob"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e441d9a9af932883c61ea3d") } > db.demo240.insertOne({"StudentName":"David"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e441d9d9af932883c61ea3e") } > db.demo240.insertOne({"StudentName":"Mike"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e441da19af932883c61ea3f") }Display all documents from a collection with the help of find() method −> db.demo240.find();This will produce the following output −{ "_id" : ObjectId("5e441d969af932883c61ea3c"), "StudentName" : "Chris" } { "_id" : ObjectId("5e441d9a9af932883c61ea3d"), "StudentName" : "Bob" } { ... Read More

For such cases, use $elemMatch. This operator matches documents that contain an array field with at least one element that matches all the specified query criteria.Let us create a collection with documents −> db.demo239.insertOne( ...   { ...      "Name" : "Chris", ...      "details" : [ ...         { "DueDate" : new ISODate("2019-01-21"), "ProductPrice" : 1270 }, ...         { "DueDate" : new ISODate("2020-02-12"), "ProductPrice" : 2000 } ...      ] ...   } ...); {    "acknowledged" : true,    "insertedId" : ObjectId("5e441c6bf4cebbeaebec5157") } > db.demo239.insertOne( ...   { ... Read More

The $unwind in MongoDB deconstructs an array field from the input documents to output a document for each element.$group is used to group input documents by the specified _id expression and for each distinct grouping, outputs a document.$project is used to pass along the documents with the requested fields to the next stage in the pipeline.Let us create a collection with documents −> db.demo238.insertOne( ...   { ... ...      "EmailId" : "John@gmail.com", ...      "details" : [ ...         { ...            "Name" : "Bob", ...         ... Read More

Set the field you don’t want to include as 0. This would display rest of the values while using find(). Let us first create a collection with documents −> db.demo237.insertOne({ ...   _id:101, ...   Product: { ...      description1: {id:1001 }, ...      description2: {Name:"Product-1" }, ...      description3: {Price:550 } ...   } ...} ...); { "acknowledged" : true, "insertedId" : 101 }Display all documents from a collection with the help of find() method −> db.demo237.find().pretty();This will produce the following output −{    "_id" : 101,    "Product" : {       "description1" : ... Read More