how to connect with mysql database and how can apply aperation on it by php code example

Example 1: php connect to mysql

$servername = "localhost";
$username = "username";
$password = "password";

// Create connection
$conn = new mysqli($servername, $username, $password);

// Check connection
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}
echo "Connected successfully";


Simplified

$conn = mysqli_connect('localhost', 'username', 'password');
$database = mysqli_select_db($conn, 'database');

Example 2: how to connect to a database in php

<?php
$servername = "localhost";
$username = "username";
$password = "password";

// Create connection
$conn = new mysqli($servername, $username, $password);

// Check connection
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}
echo "Connected successfully";
?>

Example 3: how do you connect the database

I USE JDCB
I use CONNECTION database to make connection
I create STATEMENT than I use statement to create query 
And run the query and get the RESULT SET


Connection = import java.sql.Connection;
Driver manager = import java.sql.DriverManager;
Connection connection = DriverManager.getConnection(url, userName, passWord);

Connection String Syntax:
jdbc:DataBaseType"subprotocal:Host:port:SID

After succesfully created the connect next step is STATEMENT

import java.sql.Statement;
Statement statement = connection.createStatement();

-We use createStatement() method to create the statement from our connection.
-The result we get from this type of statement can only move from top to bottom,
not other way around

Once we have statement we can run the query and get the result to
ResultSet format 
		import java.sql.ResultSet;
        
We use the method executeQuery() to execute our queries

ResultSet result = statement.executeQuery("Select * from employees");