<?php	

function getpostsby ($username, $limit=30) {
	if (strlen($username) < 1)
		return false;
	$sql = '
		SELECT 
			* 
		FROM 
			c_posts 
		WHERE 
			username = "'.mysql_real_escape_string($username).'" 
		LIMIT 
			'.$limit.'
	';
	$query = mysql_query($sql);
	if (!$query)
		return array('Error: '.mysql_error());
	if(mysql_num_rows($query) == 0)
		return false;
	$posts = array();
	while($row = mysql_fetch_array($query)) {
		$posts[] = $row;
	}
	return $posts;
}

$posts = getpostsby('Bob');

?>

Here are some posts: 

<?php

foreach ($posts as $post) {
	print '<h2>'.$post['title'].'</h2>';
	print '<p>'.$post['body'].'</p>';
}

?>

Fatal error: Call to undefined function mysql_real_escape_string() on line 12