You can use $type operator to check whether a filed contains null value. Let us first create a collection with documents. We have also inserted a null in a field −> db.nullDemo.insertOne({"FirstName":"Chris"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cc68a1eac184d684e3fa270") } > db.nullDemo.insertOne({"FirstName":null}); {    "acknowledged" : true,   ... Read More

To distribute the extra horizontal and vertical space, use the fields weightx and weighty. The following is an example to distribute extra horizontal and vertical space −Examplepackage my; import java.awt.GridBagConstraints; import java.awt.GridBagLayout; import javax.swing.JFrame; import javax.swing.JLabel; import javax.swing.JPanel; import javax.swing.JTextArea; import javax.swing.WindowConstants; public class SwingDemo {    public static void ... Read More

Here we will see how to change the output of the printf() function from main(). Here we will define a function that will change all of the printf() statements with the given type to another type.We will use the #define macro to do this task. This macro will be defined ... Read More

You can use aggregate framework. Let us first create a collection with documents −> db.topCountArrayDemo.insertOne( ...    {"StudentId":101 , "StudentSubject": ["C", "MongoDB"]} ... ); {    "acknowledged" : true,    "insertedId" : ObjectId("5cc6b3209cb58ca2b005e669") } > db.topCountArrayDemo.insertOne( ...    {"StudentId":102 , "StudentSubject": ["C", "Java"]} ... ); {    "acknowledged" : true, ... Read More

We have set a component first −GridBagConstraints constraints = new GridBagConstraints(); constraints.gridy = 0; panel.add(new JButton("First row"), constraints);Now, we will place it next to the previously added component −constraints.gridx = GridBagConstraints.RELATIVE; constraints.gridy = 1; panel.add(new JButton("2nd row 1st column"), constraints); panel.add(new JButton("2nd row 2nd column"), constraints);Examplepackage my; import java.awt.GridBagConstraints; import ... Read More

The C++ language is designed by adding some additional features like Object Oriented concepts with C. Most of the C programs can be compiled using C++ compiler also. Though there are some programs that cannot be compiled using C++ compiler.Let us see some code, that will compile in C compiler, ... Read More

To remove key fields in MongoFB, you can use $unset operator. Let us first create a collection with documents −>db.removeKeyFieldsDemo.insertOne({"StudentFirstName":"John", "StudentLastName":"Doe", "StudentAge":23}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cc6c8289cb58ca2b005e672") } >db.removeKeyFieldsDemo.insertOne({"StudentFirstName":"John", "StudentLastName":"Smith", "StudentAge":21}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cc6c8359cb58ca2b005e673") }Following is the query to display ... Read More

Here we will see three functions. These functions are trunc(), truncf() and the truncl(). These functions are used to convert floating point values into truncated form.The trunc() FunctionThis function is used to truncate double type value. And return only the integer part. The syntax is like below.double trunc(double argument)Example#include ... Read More

Yes, you can set a variable collection name in MongoDB shell using JavaScript. Let us first create a collection with documents −> db.employeeInformation.insertOne({"EmployeeName":"John Smith", "EmployeeAge":24, "EmployeeSalary":450000}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cc6d06baf8e7a4ca6b2ad97") }Following is the query to display all documents from a collection with the help of ... Read More

To get the same result like AND in MongoDB, use the $all operator. Let us first create a collection with documents −> db.andQueryDemo.insertOne({"StudentName":"Carol Taylor", "FavouriteSubject":["C", "Java", "MongoDB", "MySQL"]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cc73e7a8f9e6ff3eb0ce433") } > db.andQueryDemo.insertOne({"StudentName":"David Miller", "FavouriteSubject":["C++", "Java", "MongoDB", "SQL Server"]}); {    "acknowledged" : ... Read More