DB agnostic virtual fields

app_model.php

<?php
class AppModel extends Model {
	private $sqlMap = array(
		'mysql' => array(
			'now' => 'NOW()',
			'if' => 'IF(%1$s,%2$s,%3$s)',
			'concat' => array('CONCAT(%s)', 'implode', ','),
			'hour' => 'HOUR',
			'year' => 'YEAR',
			'date_sub' => 'DATE_SUB(%1$s, INTERVAL %2$s %3$s)',
			'date_add' => 'DATE_SUB(%1$s, INTERVAL %2$s %3$s)',
			'timestamp' => 'UNIX_TIMESTAMP(%s)',
			'lpad' => 'LPAD(%1$s, %2$s, %3$s)',
		),
		'mssql' => array(
			'now' => 'GETDATE()',
			'if' => 'CASE WHEN %1$s THEN %2$s ELSE %3$s END',
			'concat' => array('%s', 'implode', '+'),
			'hour' => 'hh',
			'year' => 'yy',
			'date_sub' => 'DATEADD(%3$s, -%2$s, %1$s)',
			'date_add' => 'DATEADD(%3$s, %2$s, %1$s)',
			'timestamp' => 'DATEDIFF(s, \'19700101\', %s)',
			'lpad' => 'replicate(%3$s, %2$s-len(%1$s))+%1$s',
		)
	);

	public function sqlMap($sql, $params = array()) {
		$driver = $this->getDataSource()->config['driver'];
		if (isset($this->sqlMap[$driver][$sql]) && !is_array($this->sqlMap[$driver][$sql])) {
			return vsprintf($this->sqlMap[$driver][$sql], $params);
		} elseif (isset($this->sqlMap[$driver][$sql]) && is_array($this->sqlMap[$driver][$sql])) {
			$params = call_user_func_array($this->sqlMap[$driver][$sql][1], array($this->sqlMap[$driver][$sql][2], $params));
			return vsprintf($this->sqlMap[$driver][$sql][0], $params);
		} else {
			return false;
		}
	}
}

//Usage:

$this->virtualFields['field_name'] = $this->sqlMap('if', array($condition, $ifTrue, $ifFalse));