/**
* Return a varchar type-formatted string
*
* @params array $values Contains a tokenised list of info about this data type
* @return string
*/
public function varchar($values)
{
$collation = MSSQLDatabase::get_collation();
$collationSQL = $collation ? " COLLATE {$collation}" : "";
return "nvarchar(" . $values['precision'] . "){$collationSQL} null";
}