如何在 Zend 框架中使用 GROUP_CONCAT?

Assume that I have a table : students

______________________________________________________
|id   | name           | school        | class        |
______________________________________________________
| 1   | John           | ABC           | C1           |
| 2   | Jack           | ABC           | C1           |
| 3   | Anna           | ABC           | C1           |
| 4   | Peter          | DEF           | D1           |
| 5   | Alex           | ABC           | C2           |
| 6   | Bryan          | ABC           | C2           |
| 7   | David          | ABC           | C2           |
| 8   | Cristian       | DEF           | D1           |
_______________________________________________________

使用此查询:

 SELECT a.class,GROUP_CONCAT(a.name) as names FROM students a WHERE a.school='ABC' GROUP BY a.class 

给我这个结果:

 ____________________________
|class  | names             |
 ____________________________
| C1    | John, Jack, Anna  |
| C2    | Alex, Bryan, David|
 ____________________________

如何在 Zend Framework 中使用 Zend_Db_Table 或 Zend_Db_Select 执行此查询?非常感谢！

$table = Your_DbTable_Class();
$select = $table->select()
          ->setIntegrityCheck(false)
          ->from(array('a' => 'students'), array( 'class' => 'class' , 'names' => new Zend_Db_Expr('GROUP_CONCAT(a.name)')) )
          ->where( 'a.school = ?', 'ABC' ) 
          ->group('a.class');

SELECT `a`.`class`, GROUP_CONCAT(a.name) AS `names` FROM `students` AS `a` 
WHERE (a.school = 'ABC')
GROUP BY `a`.`class`