Base dao class illustrating the usefulness of closures.
* Handles opening and closing of connections.
* Adds slashes sql
* Type checking of sql parameters and casts as appropriate
* Provides hook for processing of result set and emitting one or more objects.
* Provides hook for accessing underlying link and result objects.

define("userName","root");
define("password","root");
define("dbName","ahcdb");
define("hostName","localhost");

class BaseDao {

??? function getConnection()??? {
??????? $link = mysql_connect(hostName, userName, password);
??????? if (!$link)
??????????? die("Could not connect: " . mysql_error());
??????? if (!mysql_select_db(dbName))
??????????? die("Could not select database: " . mysql_error());
??????? return $link;
??? }
???
??? function setParams(& $sql, $params)??? {
??????? if($params != null)
??????????? $sql = vsprintf($sql, array_map(function($n) {
??????????????? if(is_int($n))
??????????????????? return (int)$n;
??????????????? if(is_float($n))
??????????????????? return (float)$n;
??????????????? if(is_string($n))
??????????????????? return "'".mysql_real_escape_string($n)."'";
??????????????? return mysql_real_escape_string($n);
??????????? }, $params));
??? }

??? function executeQuery($sql, $params, $callback = null)??? {
??????? $link? = $this->getConnection();
??????? $this->setParams($sql, $params);
??????? $return = null;
??????? if(($result = mysql_query($sql, $link)) != null)
??????????? if($callback != null)
??????????????? $return = $callback($result, $link);
??????? if($link != null)
??????????? mysql_close($link);
??????? if(!$result)
??????????? die("Fatal Error: Invalid query '$sql' : " . mysql_error());
??????? return $return;
??? }
?
??? function getList($sql, $params, $callback)??? {
??????? return $this->executeQuery($sql, $params, function($result, $link) use ($callback) {
??????????? $idx = 0;
??????????? $list = array();
??????????? while ($row = mysql_fetch_assoc($result))
??????????????? if($callback != null)
??????????????????? $list[$idx] = $callback($idx++, $row);
??????????? return $list;
??????? });
??? }
???
??? function getSingle($sql, $params, $callback)??? {
??????? return $this->executeQuery($sql, $params, function($result, $link) use ($callback) {
??????????? if ($row = mysql_fetch_assoc($result))
??????????????? $obj = $callback($row);
??????????? return $obj;
??????? });
??? }
}

class Example??? {
??? var $id;
??? var $name;
???
??? function Example($id, $name){
??????? $this->id = $id;
??????? $this->name = $name;
??? }
???
??? function setId($id){
??????? $this->id = $id;
??? }
}

class ExampleDao extends BaseDao??? {
???
???
??? function getAll(){
??????? return parent::getList("select * from nodes", null, function($idx, $row) {
??????????? return new Example($row["id"], $row["name"]);
??????? });
??? }
???
??? function load($id){
??????? return parent::getSingle("select * from nodes where id = %1\$s", array($id), function($row) {
??????????? return new Example($row["id"], $row["name"]);
??????? });
??? }
???
??? function update($example){
??????? return parent::executeQuery("update nodes set name = '' where? id = -1", null, function($result, $link){
??????????? return $result;
??????? });
??? }
???
??? function insert(& $example){
??????? return parent::executeQuery("insert into nodes", null, function($result, $link) use ($example){
??????????? $id = mysql_insert_id($link);
??????????? $example->setId($id);
??????????? return $result;
??????? });
??? }???
}

$exampleDao = new ExampleDao();

$list = $exampleDao->getAll());

$exampleObject = $exampleDao->load(1));

$exampleDao->update($exampleObject);

?>