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To remove, use remove() in MongoDB. Let us create a collection with documents −> db.demo309.insertOne({ "details":[ { "Name":"Chris" }, { "Name":"David" }, { "Name":"Adam" } ] } ); { "acknowledged" : true, "insertedId" : ObjectId("5e4eb71af8647eb59e562040") } > db.demo309.insertOne({ "details":[ { "Name":"David" }, { "Name":"Mike" }, { "Name":"Bob" } ] } ); { "acknowledged" : true, "insertedId" : ObjectId("5e4eb7cbf8647eb59e562041") }Display all documents from a collection with the help of find() method −> db.demo309.find();This will produce the following output −{ "_id" : ObjectId("5e4eb71af8647eb59e562040"), "details" : [ { "Name" : "Chris" }, { "Name" : "David" }, { "Name" ... Read More
To retried a subset of fields, use dot notation in find(). Let us create a collection with documents −> db.demo307.insertOne({ ... "CleintId":101, ... "ClientDetails":{"ClientFirstName":"Chris", "Age":34}, ... "ClientCountryName":"US" ...} ...); { "acknowledged" : true, "insertedId" : ObjectId("5e4eab88f8647eb59e56203c") } > db.demo307.insertOne({ ... "CleintId":102, ... "ClientDetails":{"ClientFirstName":"David", "Age":31}, ... "ClientCountryName":"UK" ...} ...); { "acknowledged" : true, "insertedId" : ObjectId("5e4eab97f8647eb59e56203d") }Display all documents from a collection with the help of find() method −> db.demo307.find();This will produce the following output −{ "_id" : ObjectId("5e4eab88f8647eb59e56203c"), "CleintId" : 101, "ClientDetails" : { "ClientFirstName" : "Chris", "Age" : 34 ... Read More
To fetch documents, use find() in MongoDB. With that, to format the resultant documents, use pretty().Let us create a collection with documents −> db.demo306.insertOne({"Name":"Robert", "Age":21}); { "acknowledged" : true, "insertedId" : ObjectId("5e4ea7c6f8647eb59e562038") } > db.demo306.insertOne({"Name":"David", "Age":23}); { "acknowledged" : true, "insertedId" : ObjectId("5e4ea7cdf8647eb59e562039") } > db.demo306.insertOne({"Name":"Mike", "Age":25}); { "acknowledged" : true, "insertedId" : ObjectId("5e4ea7d4f8647eb59e56203a") } > db.demo306.insertOne({"Name":"Carol", "Age":26}); { "acknowledged" : true, "insertedId" : ObjectId("5e4ea7dcf8647eb59e56203b") }Display all documents from a collection with the help of find() method −> db.demo306.find().pretty();This will produce the following output −{ "_id" : ObjectId("5e4ea7c6f8647eb59e562038"), "Name" : ... Read More
To get the child of a collection in MongoDB, use find(). Let us create a collection with documents −> db.demo305.insertOne( ... { ... _id: 101, ... FirstName : 'Chris', ... details : { ... "0":"102", ... "1":"10001" ... } ... } ...); { "acknowledged" : true, "insertedId" : 101 } > db.demo305.insertOne( ... { ... _id: 102, ... FirstName : 'David', ... details : { ... "0":"103", ... "1":"10002" ... } ... } ...); { "acknowledged" : true, "insertedId" : 102 }Display all documents from a collection with the help of find() method −> db.demo305.find();This will produce the following output −{ "_id" : 101, "FirstName" : "Chris", "details" : { "0" : "102", "1" : "10001" } } { "_id" : 102, "FirstName" : "David", "details" : { "0" : "103", "1" : "10002" } }Following is the query to get the child of a MongoDB collection by the key −> db.demo305.find({_id:102},{'details.0':1});This will produce the following output −{ "_id" : 102, "details" : { "0" : "103" } }
Use $or operator to fetch values and to format the result, use “pretty()”. Let us create a collection with documents −> db.demo304.insertOne({"StudentName":"Chris", "StudentAge":23}); { "acknowledged" : true, "insertedId" : ObjectId("5e4ea3ccf8647eb59e562034") } > db.demo304.insertOne({"StudentName":"David", "StudentAge":22}); { "acknowledged" : true, "insertedId" : ObjectId("5e4ea3d7f8647eb59e562035") } > db.demo304.insertOne({"StudentName":"Mike", "StudentAge":24}); { "acknowledged" : true, "insertedId" : ObjectId("5e4ea3e2f8647eb59e562036") } > db.demo304.insertOne({"StudentName":"Carol", "StudentAge":22}); { "acknowledged" : true, "insertedId" : ObjectId("5e4ea3eef8647eb59e562037") }Display all documents from a collection with the help of find() method −> db.demo304.find();This will produce the following output −{ "_id" : ObjectId("5e4ea3ccf8647eb59e562034"), "StudentName" : "Chris", "StudentAge" : 23 ... Read More
For distinct values, use distinct(). Let us create a collection with documents −> db.demo303.insertOne({FirstName:"Chris", LastName:"Brown"}); { "acknowledged" : true, "insertedId" : ObjectId("5e4ea0f6f8647eb59e56202f") } > db.demo303.insertOne({FirstName:"John", LastName:"Doe"}); { "acknowledged" : true, "insertedId" : ObjectId("5e4ea104f8647eb59e562030") } > db.demo303.insertOne({FirstName:"Chris", LastName:"Smith"}); { "acknowledged" : true, "insertedId" : ObjectId("5e4ea10df8647eb59e562031") } > db.demo303.insertOne({FirstName:"John", LastName:"Smith"}); { "acknowledged" : true, "insertedId" : ObjectId("5e4ea121f8647eb59e562032") } > db.demo303.insertOne({FirstName:"David", LastName:"Miller"}); { "acknowledged" : true, "insertedId" : ObjectId("5e4ea136f8647eb59e562033") }Display all documents from a collection with the help of find() method −> db.demo303.find().pretty();This will produce the following output −{ "_id" : ObjectId("5e4ea0f6f8647eb59e56202f"), ... Read More
For this, use dot notation for field selection in MongoDB find(). Let us create a collection with documents −> db.demo302.insertOne({"Id":101, "details":[{"Name":"Chris", Age:21, "Subject":"MySQL"}]}); { "acknowledged" : true, "insertedId" : ObjectId("5e4d746f5d93261e4bc9ea52") } > db.demo302.insertOne({"Id":102, "details":[{"Name":"Bob", Age:23, "Subject":"MongoDB"}]}); { "acknowledged" : true, "insertedId" : ObjectId("5e4d74815d93261e4bc9ea53") } > db.demo302.insertOne({"Id":103, "details":[{"Name":"David", Age:20, "Subject":"Java"}]}); { "acknowledged" : true, "insertedId" : ObjectId("5e4d74955d93261e4bc9ea54") }Display all documents from a collection with the help of find() method −> db.demo302.find();This will produce the following output −{ "_id" : ObjectId("5e4d746f5d93261e4bc9ea52"), "Id" : 101, "details" : [ { "Name" : "Chris", "Age" : 21, "Subject" : ... Read More
Use swap concept to change the order of array elements. Let us create a collection with documents −> db.demo301.insertOne({"Name":["Chris", "David", "Bob"]}); { "acknowledged" : true, "insertedId" : ObjectId("5e4d6ff55d93261e4bc9ea51") }Display all documents from a collection with the help of find() method −> db.demo301.find();This will produce the following output −{ "_id" : ObjectId("5e4d6ff55d93261e4bc9ea51"), "Name" : [ "Chris", "David", "Bob" ] }Following is the query to change the order of array elements −> db.demo301.find({}, { Name : 1 }).forEach(function(n) { ... var t = n.Name[0]; ... n.Name[0] = n.Name[1]; ... n.Name[1] = t; ... db.demo301.update({ _id: n._id ... Read More
For exact array matching, simply use find() in MongoDB. Let us create a collection with documents −> db.demo300.insertOne({"Values":[100, 200, 400]}); { "acknowledged" : true, "insertedId" : ObjectId("5e4d69d05d93261e4bc9ea4d") } > db.demo300.insertOne({"Values":[500, 700, 900, 1000]}); { "acknowledged" : true, "insertedId" : ObjectId("5e4d69dd5d93261e4bc9ea4e") } > db.demo300.insertOne({"Values":[340, 670, 450, 500]}); { "acknowledged" : true, "insertedId" : ObjectId("5e4d69eb5d93261e4bc9ea4f") }Display all documents from a collection with the help of find() method −> db.demo300.find();This will produce the following output −{ "_id" : ObjectId("5e4d69d05d93261e4bc9ea4d"), "Values" : [ 100, 200, 400 ] } { "_id" : ObjectId("5e4d69dd5d93261e4bc9ea4e"), "Values" : [ 500, 700, 900, ... Read More
To access an object in an array, use dot notation. Let us create a collection with documents −> db.demo299.insertOne( ... { ... "id":100, ... "Name":"Robert", ... "details":[ ... { ... "SubjectName":["C++", "Python"] ... }, ... { ... "SubjectName":["Spring", "Hibernate"] ... } ... ] ... } ...); { "acknowledged" : true, "insertedId" : ObjectId("5e4d685a5d93261e4bc9ea4b") } > > > db.demo299.insertOne( ... { ... ... Read More