SqlHelper::formatDate

public function formatDate($format, $field = null);

/**
 * Returns function for getting part of string.
 * 

 * If length is null or omitted, the substring starting
 * from start until the end of the string will be returned.
 * 

 * $str and $from parameters are SQL unsafe.
 *
 * @param string $str Database field or expression.
 * @param integer $from Start position.
 * @param integer $length Maximum length.
 *
 * @return string
 */
public function getSubstrFunction($str, $from, $length = null)
{
	$sql = 'SUBSTR('.$str.', '.$from;

	if (!is_null($length))
		$sql .= ', '.$length;

	return $sql.')';
}