You need to use changeUserPassword() to change a user’s password. Let us first create a user with some roles. Following is the query to create a user in MongoDB −> use admin switched to db admin > db.createUser( ...    { ...       user: "Chris", ...     ... Read More

To push elements to an existing array, use $addToSet operator along with update(). Let us first create a collection with documents −> db.pushElements.insertOne({"Comments":["Good", "Awesome", "Nice"]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cd682597924bb85b3f48953") }Following is the query to display all documents from a collection with the help of find() ... Read More

Here we will see the Shuffle and random_shuffle in C++. Let us see the random_shuffle first. It is used to randomly rearrange the elements in range [left, right). This function randomly swaps the positions of each element with the position of some randomly chosen positions.We can provide some random generator ... Read More

This is a C++ program to repeatedly search the same text.AlgorithmsBegin    Take the original string and pattern to be searched as input.    org_len = store the length of original string    pat_len = store the length of pattern    for i = 0 to (org_len - pat_len)   ... Read More

For this, use printjson. Let us first create a collection with documents −> db.cursorDemo.insertOne({"StudentFullName":"John Smith", "StudentAge":23}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cc7f0d08f9e6ff3eb0ce442") } > db.cursorDemo.insertOne({"StudentFullName":"John Doe", "StudentAge":21}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cc7f0df8f9e6ff3eb0ce443") } > db.cursorDemo.insertOne({"StudentFullName":"Carol Taylor", "StudentAge":20}); {    "acknowledged" : true,   ... Read More

You can use $group operator with _id: null. Following is the syntax −db.yourCollectionName.aggregate([{$group: {_id:null, "anyFieldName": {$avg:"$yourFieldName"} } }]);Let us first create a collection with documents −> db.caculateTheAverageValueDemo.insertOne({"Population":100}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cd68a197924bb85b3f4895f") } > db.caculateTheAverageValueDemo.insertOne({"Population":500}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cd68a1c7924bb85b3f48960") } > ... Read More

This example demonstrate about Custom Notification Sounds for Android Oreo and BeyondStep 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.     Step 3 ... Read More

This is a C++ program in which we generate a undirected random graph for the given edges ‘e’. This algorithm basically implements on a big network and time complexity of this algorithm is O(log(n)).AlgorithmBegin    Function GenerateRandomGraphs(), has ‘e’ as the number edges in the argument list.    Initialize i ... Read More

Here we will see how the copy constructors are implemented in C++. Before discussing that we should know what is the copy constructor.The copy constructor is a constructor which creates an object by initializing it with an object of the same class, which has been created previously. The copy constructor ... Read More

You can use $eq as well as $ne operator for boolean values. Let us first create a collection with documents −> db.booleanQueryDemo.insertOne({"UserName":"John", "UserAge":23, "isMarried":true}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cc815c08f9e6ff3eb0ce44a") } > db.booleanQueryDemo.insertOne({"UserName":"Chris", "UserAge":21, "isMarried":false}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cc815d08f9e6ff3eb0ce44b") } > db.booleanQueryDemo.insertOne({"UserName":"Robert", ... Read More