php.md

Variable

Global

$x = 1;
$y = 2;

function test1(){
  global $x,$y;
  echo $x+$y;
}

function test2(){
  echo $GLOBALS["x"]+$GLOBALS["y"];
}

test1(); //3
test2(); //3

Class

Basic

class Human {
  protected $name;
  function __construct($name){
    $this->name = $name;
  }
  function greeting(){
    echo "Hi my name is $this->name!\n";
  }
}

$derek = new Human("Derek");
$derek->greeting(); //Hi my name is Derek!

Inherit

class Human {
  protected $name;
  function __construct($name){
    $this->name = $name;
  }
  function greeting(){
    echo "Hi my name is $this->name!\n";
  }
}

class Adult extends Human{ 
  protected $job; 
  function __construct($name,$job){
    parent::__construct($name); //Use parent constructor
    $this->job = $job;
  }
  function greeting(){
    echo "Hi my name is $this->name!\nI am an $this->job!\n";
  }
}
$derek = new Adult("Derek","enginner");
$derek->greeting();

MySQL

Query

$mysqli = new mysqli("host", "user", "pw", "db");
$mysqli->set_charset ('utf8');

$data = $mysqli->query("SELECT * FROM user WHERE id=1")->fetch_all();

$mysqli->close();

Prepare statement

MySQLi

$mysqli = new mysqli("host", "user", "pw", "db");
$mysqli->set_charset ('utf8');

$stmt = $mysqli->prepare("SELECT * FROM user WHERE id=?");
$stmt->bind_param("i", $id);

$id = 1;
$stmt->execute();
$data = $stmt->get_result()->fetch_all();
// $data = $stmt->get_result()->fetch_array();
// $data = $stmt->get_result()->fetch_row();
// $data = $stmt->get_result()->fetch_assoc();

$mysqli->close();

PDO

$servername = "host";
$username = "user";
$password = "pw";
$dbname = "db";

try {
    $conn = new PDO("mysql:host=$servername;dbname=$dbname;charset=utf8", $username, $password);
    $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

    $stmt = $conn->prepare("SELECT * from user where id = :id;");
    $stmt->bindParam(':id', $id);

    $id = 1;
    $stmt->execute();
    $data = $stmt->fetch(PDO::FETCH_ASSOC);
    print_r($data);
  }catch(PDOException $e){
    echo "Error: " . $e->getMessage();
  }
$conn = null;