To project specific fields from a document inside an array, you can use positional ($) operator.Let us first create a collection with documents> db.projectSpecificFieldDemo.insertOne(    ... {       ... "UniqueId": 101,       ... "StudentDetails" : [{"StudentName" : "Chris", "StudentCountryName ": "US"},          ... ... Read More

To count null values in MySQL, you can use CASE statement. Let us first see an example and create a table −mysql> create table DemoTable (    Id int NOT NULL AUTO_INCREMENT PRIMARY KEY,    FirstName varchar(20) ); Query OK, 0 rows affected (0.77 sec)Insert some records in the table ... Read More

You can use the COALESCE() function to convert MySQL null to 0SELECT COALESCE(yourColumnName, 0) AS anyAliasName FROM yourTableName;Let us first create a table. The query to create a table is as followsmysql> create table convertNullToZeroDemo    -> (    -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY,    -> Name ... Read More

To get number of updated documents in MongoDB, you need to use runCommand along with getlasterror.Let us first create a collection with documents> db.getNumberOfUpdatedDocumentsDemo.insertOne({"StudentName":"David"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5ca28c1d6304881c5ce84bad") } > db.getNumberOfUpdatedDocumentsDemo.insertOne({"StudentName":"Chris"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5ca28c226304881c5ce84bae") } > db.getNumberOfUpdatedDocumentsDemo.insertOne({"StudentName":"Robert"}); {   ... Read More

Following is an example that passes two values using the HTML FORM and the submit button. We are going to use the same JSP main.jsp to handle this input.                    First Name:                 ... Read More

You can use GROUP_CONCAT() function to list all the items in a group in one record. Let us first create a table −mysql> create table DemoTable (    ProductId int,    ProductName varchar(40),    ProductCategory varchar(40) ); Query OK, 0 rows affected (0.67 sec)Insert some records in the table using ... Read More

Let us firs create a tablemysql> create table LimitWithStoredProcedure    -> (    -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY,    -> Name varchar(10)    -> ); Query OK, 0 rows affected (0.47 sec)Insert some records in the table using insert command.The query is as followsmysql> insert into LimitWithStoredProcedure(Name) ... Read More

Here we will see how to generate hollow pyramid and diamond patterns using C. We can generate solid Pyramid patterns very easily. To make it hollow, we have to add some few tricks.Hollow PyramidFor the pyramid at the first line it will print one star, and at the last line ... Read More

Servlet and JSP Filters are Java classes that can be used in Servlet and JSP Programming for the following purposes To intercept requests from a client before they access a resource at the back end.To manipulate responses from the server before they are sent back to the client.There are various types ... Read More

The flatMap() method of the IntStream class returns a stream consisting of the results of replacing each element of this stream with the contents of a mapped stream produced by applying the provided mapping function to each element.The syntax is as followsIntStream flatMap(IntFunction