php connect to mysql

1<?php
2$servername = "localhost";
3$username = "username";
4$password = "password";
5$dbname = "myDB";
6
7// Create connection
8$conn= mysqli_connect($servername,$username,$password,$dbname);
9// Check connection
10if (!$conn) {
11  die("Connection failed: " . mysqli_connect_error());
12}
13echo "Connected Successfully.";
14?>

1$servername = "localhost";
2$username = "username";
3$password = "password";
4
5// Create connection
6$conn = new mysqli($servername, $username, $password);
7
8// Check connection
9if ($conn->connect_error) {
10    die("Connection failed: " . $conn->connect_error);
11}
12echo "Connected successfully";
13
14
15Simplified
16
17$conn = mysqli_connect('localhost', 'username', 'password');
18$database = mysqli_select_db($conn, 'database');

1<?php
2    $user = "username";
3    $pass = "password";
4    $host = "host";
5    $dbdb = "database";
6    
7$conn = new mysqli($host, $user, $pass, $dbdb);
8   if ($conn->connect_error) {
9    die("Connection failed: " . $conn->connect_error);
10} 
11?>

1# MySql improved
2<?php
3    $mysqli = new mysqli("localhost", "username", "password", "dbname");
4	$result = $mysqli->query("SELECT lastname FROM employees");
5?>
6# Connection with PDO
7<?php
8    $myPDO = new PDO('mysql:host=localhost;dbname=dbname', 'username', 'password');
9	$result = $myPDO->query("SELECT lastname FROM employees");
10?>
11# With PHP legacy functions:
12<?php
13    mysql_connect('localhost','username','password');
14    mysql_select_db("dbname");
15	$result = mysql_query('SELECT lastname FROM employees');
16?>

1Just include this Temlate in other file using PHP Include/Require Keywords
2 And Make Connection In One Shot :)
3
4<?php
5  
6    // echo "Welcome to Connecting of DB Tutorial!";
7    // echo "<br>";
8
9    // 1. PDO - Php Data Objects
10    // 2. MySQLi extension
11
12    // Set Connection Variable
13    $server = "localhost";
14    $username = "root";
15    $password = "";
16    $database = "test";
17
18    // Create A Connection
19    $con = mysqLi_connect($server, $username, $password, $database);
20
21     // Check For Connection
22     if(!$con){
23        die ("Connection Terminated! by Die() function". mysqLi_connect_error());
24       
25    }
26    else {
27        echo "Connection Succefully Happened! <br>";
28    }
29
30
31    ?>

1<?php
2$servername = "localhost";
3$username = "username";
4$password = "password";
5
6// Create connection
7$conn = new mysqli($servername, $username, $password);
8
9// Check connection
10if ($conn->connect_error) {
11    die("Connection failed: " . $conn->connect_error);
12}
13echo "Connected successfully";
14?>