Zend FR

SELECT t1_label, t2_label
FROM table1
INNER JOIN (SELECT t2_label FROM table2 WHERE condition) AS T2 ON (table1.t2_id = T2.t2_id)

$db->select()
->from ('table1', array('t1_label')
->joinInner(
      array('T2' => new Zend_Db_Expr (
         '('.
         $db->select()
         ->from('table2', array('t2_label'))
         ->where('condition')
         .')'
      )),
      'table1.t2_id = T2.t2_id',
      array('t2_label')
)

SELECT
`table2`.`t2_label`
FROM `table2`
WHERE condition

(SELECT
`table2`.`t2_label`
FROM `table2`
WHERE condition)

`(SELECT
``table2```.```t2_label``
FROM ``table2``
WHERE condition)`

        if (false !== strpos($tableName, '.')) {
            list($schema, $tableName) = explode('.', $tableName);
        }

        if (!$tableName instanceof Zend_Db_Expr && false !== strpos($tableName, '.')) {
            list($schema, $tableName) = explode('.', $tableName);
        }