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Articles on Trending Technologies
Technical articles with clear explanations and examples
MySQL query to combine two columns in a single column?
You can use COALESCE() function for this. In the COALESCE() function, it returns the first NON NULL value from the column. To understand the concept, let us first create a demo tablemysql> create table combineTwoColumnsDemo -> ( -> UserId int, -> UserName varchar(20), -> UserAge int -> ); Query OK, 0 rows affected (1.12 sec)Insert some records in the table using insert command. The query is as follows −mysql> insert into combineTwoColumnsDemo values(101, 'John', 23); Query OK, 1 row affected (0.16 sec) mysql> insert into combineTwoColumnsDemo values(102, 'Carol', 20); Query OK, 1 row affected (0.14 ...
Read MoreThe get() method of AbstractList class in Java
The get() method of the AbstractList class is used to get the element at the specified position in the list. It returns the element at the position set as parameter.The syntax is as follows:public abstract E get(int index)Here, index is the index of the element to return.To work with the AbstractList class, import the following package:import java.util.AbstractList;The following is an example to implement get() method of the AbstractlList class in Java:Exampleimport java.util.LinkedList; import java.util.AbstractList; public class Demo { public static void main(String[] args) { AbstractList myList = new LinkedList(); myList.add(50); ...
Read MoreAdding Navigation Bar programmatically iOS using Swift
To add navigation bar programmatically we’ll go through a series of steps that are mentioned below. We’ll be doing this in ViewWillLayoutSubviews method of our viewController.Getting the width of the current View.let width = self.view.frame.widthCreating a navigation bar with the width of our current view and height of 44 px which is the default height of a navigation bar.let navigationBar: UINavigationBar = UINavigationBar(frame: CGRect(x: 0, y: 0, width: width, height: 44))Adding the newly created navigation bar to our view.self.view.addSubview(navigationBar)We can further extend this example to add a title and a button to our View. The complete result should look something ...
Read MoreDrop a MySQL Table after x hours?
You need to create event to drop table after x hours. The syntax is as follows −CREATE EVENT yourEventName ON SCHEDULE AT CURRENT_TIMESTAMP + INTERVAL x HOUR DO DROP TABLE IF EXISTS yourTableName;Let us first create a table −mysql> create table DemoTable ( StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY, StudnetFirstName varchar(20), StudentLastName varchar(20), StudnetAge int ); Query OK, 0 rows affected (0.52 sec)Now implement the above event in order to drop table after 2 hours −mysql> CREATE EVENT drop_table_event_after2HoursDemo ON SCHEDULE AT CURRENT_TIMESTAMP + INTERVAL 2 HOUR DO DROP TABLE IF EXISTS DemoTable; Query OK, ...
Read More8085 Program to simulate decimal down counter
Now let us see a program of Intel 8085 Microprocessor. In this program we will see how to simulate the decimal down counter.Problem Statement:Write 8085 Assembly language program to simulate decimal down counter.Discussion:In this section we are simulating the decimal down counter. Here the counter will count 100 decimal numbers from 99 to 0. All values will be updated in each 0.5 seconds. For decimal count we are using the DAA instruction.Note: Here for simplicity we are storing the numbers into memory. To simulate it like a counter we can use 7-segment display to show the numbersInput:Here we are not ...
Read MoreWhat is the use of setFetchSize() and setMaxRows() methods of the JDBC Statement Interface?
The setFetchSize(int) method defines the number of rows that will be read from the database when the ResultSet needs more rows. setFetchSize(int) affects how the database returns the ResultSet data.Whereas, setMaxRows(int) method of the ResultSet specifies how many rows a ResultSet can contain at a time. setMaxRows(int) affects the client side JDBC object.
Read MoreHow to find middle element in a linked list in android?
This example demonstrate about How to finding middle element in a linked list in android.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. In the above code, we have taken a text view to find the middle element.Step 3 − Add the following code to src/MainActivity.javapackage com.example.myapplication; import android.os.Build; import android.os.Bundle; import android.support.annotation.RequiresApi; import android.support.v7.app.AppCompatActivity; import android.widget.TextView; import java.util.LinkedList; public class MainActivity extends AppCompatActivity { @RequiresApi(api ...
Read MoreHow to efficiently perform “distinct” with multiple keys in MongoDB?
You can perform distinct with multiple keys with the help of an aggregate framework.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.distinctWithMultipleKeysDemo.insertOne({"StudentName":"Mike", "StudentAge":22, "StudentMathMarks":56}); { "acknowledged" : true, "insertedId" : ObjectId("5c7f74488d10a061296a3c53") } > db.distinctWithMultipleKeysDemo.insertOne({"StudentName":"Mike", "StudentAge":22, "StudentMathMarks":56}); { "acknowledged" : true, "insertedId" : ObjectId("5c7f744b8d10a061296a3c54") } > db.distinctWithMultipleKeysDemo.insertOne({"StudentName":"Bob", "StudentAge":23, "StudentMathMarks":45}); { "acknowledged" : true, "insertedId" : ObjectId("5c7f74598d10a061296a3c55") } > db.distinctWithMultipleKeysDemo.insertOne({"StudentName":"Bob", "StudentAge":23, "StudentMathMarks":45}); { "acknowledged" : true, "insertedId" : ObjectId("5c7f745e8d10a061296a3c56") } > db.distinctWithMultipleKeysDemo.insertOne({"StudentName":"Carol", "StudentAge":27, "StudentMathMarks":54}); { "acknowledged" ...
Read MoreHandling optional/empty data in MongoDB?
In order to handle empty data, you can use $ne operator. Let us create a collection with documents. Following is the query>db.handlingAndEmptyDataDemo.insertOne({"StudentName":"John", "StudentCountryName":""}); { "acknowledged" : true, "insertedId" : ObjectId("5c9cbd5ca629b87623db1b12") } >db.handlingAndEmptyDataDemo.insertOne({"StudentName":"John", "StudentCountryName":null}); { "acknowledged" : true, "insertedId" : ObjectId("5c9cbd6ba629b87623db1b13") } > db.handlingAndEmptyDataDemo.insertOne({"StudentName":"John"}); { "acknowledged" : true, "insertedId" : ObjectId("5c9cbd71a629b87623db1b14") }Following is the query to display all documents from a collection with the help of find() method> db.handlingAndEmptyDataDemo.find().pretty();This will produce the following output{ "_id" : ObjectId("5c9cbd5ca629b87623db1b12"), "StudentName" : "John", "StudentCountryName" : "" } { "_id" : ObjectId("5c9cbd6ba629b87623db1b13"), "StudentName" : ...
Read MoreCounting number of positive and negative votes in MySQL?
To count number of positive and negative votes, you can use CASE statement along with aggregate function SUM().Let us first create a table −mysql> create table DemoTable ( Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, Vote int ); Query OK, 0 rows affected (1.70 sec)Insert some records in the table using insert command −mysql> insert into DemoTable(Vote) values(-10); Query OK, 1 row affected (0.20 sec) mysql> insert into DemoTable(Vote) values(100); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable(Vote) values(45); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable(Vote) values(-6); Query OK, 1 row ...
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