For this, use $group along with $max in MongoDB. Let us create a collection with documents −> db.demo510.insertOne( ... { ...    details:[ ...       { ...          Name:"Chris", ...          Score:56 ...       }, ...       { ... 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" : [ ...     ... 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 ... 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 ... 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"}, ...   ... 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", ...     ... 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 ... 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 ... 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" ... Read More

To query an array of subdocuments, use $unwind in MongoDB. Let us create a collection with documents −> db.demo499.insertOne({ ... "details": ...    [ ...       { ...          Name :"MIT", ...          Rank: 1, ...          "CountryName":"US" ... ... Read More