<!-- Collection of code snippets by Arne Vajhøj -->
<!-- (from articles on eksperten.dk / vajhoej.dk written sometime between 2004 and now) -->
<?php

class Problem extends Exception {
}

abstract class DB {
	public function setup() {
		$con = $this->getConnection();
		$con->query("INSERT INTO tblsrc VALUES(1,10)");
		$con->query("INSERT INTO tbltrg VALUES(1,0)");
	}
	public function teardown() {
		$con = $this->getConnection();
		$con->query("DELETE FROM tblsrc WHERE id = 1");
		$con->query("DELETE FROM tbltrg WHERE id = 1");
	}
	public function check() {
		$con = $this->getConnection();
		$rs = $con->query("SELECT val FROM tblsrc WHERE id = 1");
		if($row = $rs->fetch_assoc()) {
			$val = $row["val"];
			echo "source val = $val\r\n";
		}
		$rs = $con->query("SELECT val FROM tbltrg WHERE id = 1");
		if($row = $rs->fetch_assoc()) {
			$val = $row["val"];
			echo "source val = $val\r\n";
		}
	}
    public abstract function getConnection();
	public abstract function test();
	public static function demo(DB $db) {
		$db->setup();
		$db->check();
		$db->test();
		$db->check();
		$db->teardown();
	}
}

?>