PHP/MySQL (PDO Database) method with named parameters

db.php

<?php

/*

PHP/MySQL (PDO)  method with named parameters
---------------------------------------------
https://gist.github.com/luckyshot/9477105
Last updated: 12 Sep 17

$config = [
  'mysql' => [
    'database' => 'database',
    'user' => 'root',
    'pass' => 'root'
  ],
];

$db = new DB(
	$config['mysql']['user'],
	$config['mysql']['pass'],
	$config['mysql']['database']
);

$select = $db->query("SELECT * FROM items WHERE id = :id")
	->bind(':id', $id)
	->select();

$single = $db->query("SELECT * FROM items WHERE id = :id LIMIT 1")
	->bind(':id', $id)
	->single();

// Returns the inserted ID
$insert = $db->query("INSERT INTO items SET
		aaa = :aaa,
		bbb = :bbb
	")
	->bind(':aaa', $aaa )
	->bind(':bbb', $bbb )
	->insert();

$update = $db->query("UPDATE items SET
		aaa = :aaa
		WHERE id = :id;
	")
	->bind(':aaa', $aaa )
	->bind(':id', $data['id'])
	->execute();

$delete = $db->query("DELETE FROM items
		WHERE id = :id
	  LIMIT 1;
	 ")
	->bind(':id', $data['id'])
	->execute();


DEBUG:
echo "<pre>";var_export( $this->db->queries );echo "</pre>";


*/

class DB {

	private $dbh;
	private $stmt;
	private $q;

	public $queries = [];

	public function __construct($user, $pass, $dbname) {
		$this->dbh = new PDO(
			"mysql:host=127.0.0.1;dbname=$dbname",
			$user,
			$pass,
			array( PDO::ATTR_PERSISTENT => true )
		);
		$this->dbh->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
		$this->query("SET NAMES 'utf8';");
		$this->execute();
	}

	public function query($query) {
		$this->queries[] = $query;

		$this->stmt = $this->dbh->prepare($query);
		return $this;
	}

	public function bind($pos, $value, $type = null) {

		if ( is_numeric( $value ) ){ $this->queries[ count($this->queries)-1 ] = str_replace( $pos, $value, $this->queries[ count($this->queries)-1 ] ); }
		else{ $this->queries[ count($this->queries)-1 ] = str_replace( $pos, '"' . $value . '"', $this->queries[ count($this->queries)-1 ] ); }

		if ( is_null($type) ) {
			switch( true ) {
				case is_int($value):
					$type = PDO::PARAM_INT;
					break;
				case is_bool($value):
					$type = PDO::PARAM_BOOL;
					break;
				case is_null($value):
					$type = PDO::PARAM_NULL;
					break;
				default:
					$type = PDO::PARAM_STR;
			}
		}

		$this->stmt->bindValue($pos, $value, $type);
		return $this;
	}

	public function execute() {
		try{
			$result = $this->stmt->execute();
		}catch(PDOException $e){
			echo '<pre>';
			var_export( $e );
			var_export( $this->dbh->errorInfo() );
			var_export( $this->queries );
		}
		return $result;
	}

	public function update() {
		return $this->execute();
	}

	public function delete() {
		return $this->execute();
	}

	// Same as execute() but returns ID
	public function insert() {
		$this->execute();
		return $this->dbh->lastInsertId();
	}

	public function select( $fetch_style = null ) {
		$this->execute();
		return $this->stmt->fetchAll( PDO::FETCH_ASSOC );
	}

	public function single( $fetch_style = null ) {
		$this->execute();
		return $this->stmt->fetch( PDO::FETCH_ASSOC );
	}
}