You can use distinct() to return only unique values. The syntax is as follows −db.yourCollectionName.distinct("yourFieldName");To understand the concept, let us create a collection with the document. The query to create a collection with a document is as follows −> db.returnOnlyUniqueValuesDemo.insertOne({"CusomerName":"Larry", "CustomerAge":23}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c8ed7262f684a30fbdfd580") ... Read More

In this section, we will see what are the differences between *ptr++, *++ptr and ++*ptr in C++.Here we will see the precedence of postfix++ and prefix++ in C or C++. The precedence of prefix ++ or -- has higher priority than dereference operator ‘*’ and postfix ++ or -- has ... Read More

This example demonstrate about How to use toLowerCase () in Android textview.Step 1 − Create a new project in Android Studio, go to File ⇒ New Project and fill all required details to create a new project.Step 2 − Add the following code to res/layout/activity_main.xml.         ... Read More

You can use the $exists and $ne operator for this. To understand the concept further, let us create a collection with document. The query to create a collection with document is as follows −> db.checkFieldExistDemo.insertOne({"EmployeeId":1, "EmployeeName":"John", "isMarried":true, "EmployeeSalary":4648585}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c76f7b31e9c5dd6f1f78281") } > db.checkFieldExistDemo.insertOne({"StudentId":2, ... Read More

To get sum the value of a key across all documents in a MongoDB collection, you can use aggregate().To understand the above concept, let us create a collection with the document. The query to create a collection with a document is as follows −> db.sumOfValueDemo.insertOne({"Name":"Larry", "Amount":14.50}); {    "acknowledged" : ... Read More

A Hamiltonian cycle is a Hamiltonian Path such that there is an edge (in graph) from the last vertex to the first vertex of the Hamiltonian Path. It is in an undirected graph is a path that visits each vertex of the graph exactly once.Functions and purposesBegin    1. function ... Read More

In order to display the indexes of a collection, you can use getIndexes(). The syntax is as follows −db.yourCollectionName.getIndexes();To understand the concept, let us create a collection with the document. The query to create a collection with a document is as follows −> db.indexDemo.insertOne({"StudentName":"Larry", "StudentAge":21}); {    "acknowledged" : true, ... Read More

You can use distinct() method in MongoDB to get distinct record values. The syntax is as follows −db.yourCollectionName.distinct(“yourFieldName”);To understand the above syntax, let us create a collection with document. The query to create a collection with document is as follows −> db.distinctRecordDemo.insertOne({"StudentId":1, "StudentName":"John", "StudentAge":21}); {    "acknowledged" : true,   ... Read More

To sort in MongoDB, you can use the sort() method.Case 1 − Sort in ascending order. The syntax is as follows −db.yourCollectionName.find().sort({yourField:1});Case 2 − Sort in descending order. The syntax is as follows −db.yourCollectionName.find().sort({yourField:-1});To understand the concept, let us create a collection with the document. The query to create a ... Read More

A reference variable is an alias, that is, another name for an already existing variable. Once a reference is initialized with a variable, either the variable name or the reference name may be used to refer to the variable.References vs PointersReferences are often confused with pointers but three major differences ... Read More