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For specific documents, use MongoDB $in. Let us create a collection with documents −> db.demo511.insertOne({"ListOfProject":["Library Management System", "Hospital Management System"]}); { "acknowledged" : true, "insertedId" : ObjectId("5e88473a987b6e0e9d18f585") } > db.demo511.insertOne({"ListOfProject":["Online Web Tracking", "Library Management System"]}); { "acknowledged" : true, "insertedId" : ObjectId("5e884751987b6e0e9d18f586") } > db.demo511.insertOne({"ListOfProject":["Online Shopping Cart", "Hospital Management System"]}); { "acknowledged" : true, "insertedId" : ObjectId("5e884776987b6e0e9d18f587") }Display all documents from a collection with the help of find() method −> db.demo511.find();This will produce the following output −{ "_id" : ObjectId("5e88473a987b6e0e9d18f585"), "ListOfProject" : [ "Library Management System", "Hospital Management System" ] } { "_id" : ... Read More
For this, use $group along with $max in MongoDB. Let us create a collection with documents −> db.demo510.insertOne( ... { ... details:[ ... { ... Name:"Chris", ... Score:56 ... }, ... { ... Name:"David", ... Score:45 ... } ... ] ... } ... ); { "acknowledged" : true, "insertedId" : ObjectId("5e8845fa987b6e0e9d18f582") } > db.demo510.insertOne( ... { ... details:[ ... { ... ... Read More
For this, use update() along with $addToSet. The $addToSet operator adds value to an array unless the value is already present, in which case $addToSet does nothing to that array. Let us create a collection with documents −> db.demo509.insertOne( ... { ... ... "value1" : [ ... { ... "value2" : [ ... 76, ... 14, ... 56 ... ] ... }, ... { ... Read More
Yes, you can track how many times each index is used in a query using MongoDB $indexStats. Following is the query to create an index in MongoDB −> db.demo508.createIndex({"FirstName":1}); { "createdCollectionAutomatically" : true, "numIndexesBefore" : 1, "numIndexesAfter" : 2, "ok" : 1 }Let us create a collection with documents −> db.demo508.insertOne({"FirstName":"John"});{ "acknowledged" : true, "insertedId" : ObjectId("5e883818987b6e0e9d18f578") } > db.demo508.insertOne({"FirstName":"Chris"});{ "acknowledged" : true, "insertedId" : ObjectId("5e88381b987b6e0e9d18f579") } > db.demo508.insertOne({"FirstName":"David"});{ "acknowledged" : true, "insertedId" : ObjectId("5e88381f987b6e0e9d18f57a") }Display all documents from a collection with the help of find() method −> db.demo508.find();This will ... Read More
To increment the value of an array object, use $inc. Let us create a collection with documents −>db.demo506.insertOne({"details":[{id:1, Quantity:4}, {id:2, Quantity:3}, {id:3, Quantity:2}, {id:4, Qua ntity:7}]}); { "acknowledged" : true, "insertedId" : ObjectId("5e882ed6987b6e0e9d18f576") }Display all documents from a collection with the help of find() method −> db.demo506.find().pretty();This will produce the following output −{ "_id" : ObjectId("5e882ed6987b6e0e9d18f576"), "details" : [ { "id" : 1, "Quantity" : 4 }, { "id" : 2, ... Read More
To filter and fetch, use projection along with MongoDB $filter and $match. Let us create a collection with documents −> db.demo507.insertOne( ... { ... ... "Information": ... [ ... {"Name":"John", "SubjectName":"MySQL"}, ... {"Name":"Bob", "SubjectName":"MongoDB"}, ... {"Name":"Chris", "SubjectName":"MySQL"}, ... {"Name":"David", "SubjectName":"C++"} ... ] ... } ... ); { "acknowledged" : true, "insertedId" : ObjectId("5e8836d3987b6e0e9d18f577") }Display all documents from a collection with the help of find() method −> db.demo507.find().pretty();This will produce the following output −{ "_id" : ObjectId("5e8836d3987b6e0e9d18f577"), "Information" : [ ... Read More
To sort nested array in MongoDB, use $sort. Let us create a collection with documents −> db.demo505.insertOne( ... { ... "details": [ ... { ... Name:"Chris", ... "Score":58 ... }, { ... ... Name:"Bob", ... "Score":45 ... }, { ... ... Name:"John", ... "Score":68 ... }, { ... ... Name:"David", ... "Score":46 ... } ... Read More
To find the user by name in MongoDB, use find(). Let us create a collection with documents −> db.demo504.insertOne({"Name":"Chris"});{ "acknowledged" : true, "insertedId" : ObjectId("5e8823ee987b6e0e9d18f570") } > db.demo504.insertOne({"Name":"John"});{ "acknowledged" : true, "insertedId" : ObjectId("5e8823f2987b6e0e9d18f571") } > db.demo504.insertOne({"Name":"David"});{ "acknowledged" : true, "insertedId" : ObjectId("5e8823f5987b6e0e9d18f572") }Display all documents from a collection with the help of find() method −> db.demo504.find();This will produce the following output −{ "_id" : ObjectId("5e8823ee987b6e0e9d18f570"), "Name" : "Chris" } { "_id" : ObjectId("5e8823f2987b6e0e9d18f571"), "Name" : "John" } { "_id" : ObjectId("5e8823f5987b6e0e9d18f572"), "Name" : "David" }Following is the query to find a user by ... Read More
To slice array, use a $slice operator in MongoDB. Let us create a collection with documents −> db.demo503.insertOne({_id:1, Name:"John", Subject:["MySQL", "Java", "C"]}); { "acknowledged" : true, "insertedId" : 1 } > db.demo503.insertOne({_id:2, Name:"David", Subject:["MongoDB", "C++", "Python"]}); { "acknowledged" : true, "insertedId" : 2 }Display all documents from a collection with the help of find() method −> db.demo503.find().pretty();This will produce the following output −{ "_id" : 1, "Name" : "John", "Subject" : [ "MySQL", "Java", "C" ] } { "_id" : 2, "Name" : "David", "Subject" : [ "MongoDB", "C++", ... Read More
For combination, use $concat and check the equality using $eq. Let us create a collection with documents −> db.demo502.insertOne({"FirstName":"John", "LastName":"Smith"});{ "acknowledged" : true, "insertedId" : ObjectId("5e875534987b6e0e9d18f56d") } > db.demo502.insertOne({"FirstName":"David", "LastName":"Miller"});{ "acknowledged" : true, "insertedId" : ObjectId("5e87553e987b6e0e9d18f56e") } > db.demo502.insertOne({"FirstName":"John", "LastName":"Doe"});{ "acknowledged" : true, "insertedId" : ObjectId("5e875543987b6e0e9d18f56f") }Display all documents from a collection with the help of find() method −> db.demo502.find();This will produce the following output −{ "_id" : ObjectId("5e875534987b6e0e9d18f56d"), "FirstName" : "John", "LastName" : "Smith" } { "_id" : ObjectId("5e87553e987b6e0e9d18f56e"), "FirstName" : "David", "LastName" : "Miller" } { "_id" : ObjectId("5e875543987b6e0e9d18f56f"), "FirstName" : "John", ... Read More