Zend_Db_Select: Working with JOIN's - php

Question

I have this query:
SELECT
groups.name
categories.name,
categories.label
FROM
groups
JOIN
categories
ON
(categories.group1 = groups.id
OR
categories.group2 = groups.id)
AND
groups.label = :section
AND
categories.active = 1
Now, this is my JOIN using Zend_Db_Select but it gives me array error
$select->from($dao, array('groups.name', 'categories.name', 'categories.label'))
->join(array('categories', 'categories.group1 = groups.id OR categories.group2 = groups.id'))
->where('groups.label = ?', $group)
->where('categories.active = 1');
My error:
Exception information:
Message: Select query cannot join with
another table
Does anyone know what I did wrong?
UPDATE / SOLUTION:
I've found the solution thanx to Eran. I just post the solution here in case anyone else is stuck on a problem like this one. The solution is:
$db = Zend_Registry::get('db');
$dao = new Default_Model_Db_CategoryDao('db');
$select = $dao->select();
$select->setIntegrityCheck(false)
->from(array('c' => 'categories'), array('name', 'label'))
->join(array('g' => 'groups'), 'c.group1 = g.id OR c.group2 = g.id', 'g.label')
->where('g.label = ?', $group)
->where('c.active = 1');
return $dao->fetchAll($select);

Answer 1

You are using a Zend_Db_Table_Select object. Those by default have integrity check enabled and cannot select data that is outside of their table.
You can turn it off by adding -> setIntegrityCheck(false) to the select object before querying with it.
You can read more about it in the manual under Select API -> Advanced usage