trait example

<?php

trait DatabaseInsert {
    public function insert() {
        echo "{$this->getDb()} insert\n";
    }
}

trait DatabaseUpdate {
    public function update() {
        echo "{$this->getDb()} update\n";
    }
}

trait DatabaseDelete {
    public function delete() {
        echo "{$this->getDb()} delete\n";
    }
}

class Database {
    private $db = null;
    public function __construct() {
        $this->db = 'DB Resource';
    }
    public function getDb() {
        return $this->db;
    }
}

class OnlyInsert extends Database {
    use DatabaseInsert;
}

$db = new OnlyInsert();
$db->insert(); // DB Resource insert
$db->update(); // PHP Fatal error:  Uncaught Error: Call to undefined method OnlyInsert::update() in test.php:37