Zend_DB subselect / subquery how to? - zend-framework

Question

I have this raw sql statement which I am trying to execute through Zend_DB.
$sql = 'SELECT relocationaction.id, relocationaction.vehicle, relocationaction.start, relocationaction.end, relocationaction.return ' .
'FROM relocationaction,
(SELECT vehicle, MAX(end) AS maxend
FROM relocationaction
GROUP BY vehicle) AS co2
WHERE co2.vehicle = relocationaction.vehicle
AND(relocationaction.monitor = 1)
AND (relocationaction.return IS NULL)
AND (start <= ?)
AND relocationaction.end = co2.maxend';
I have found a possible solution using this type of notation, but it is rendered to a totally different and wrong sql statement with joins and strange table names.
$tbl = $this->getDbTable();
$select = $tbl->select()->setIntegrityCheck(false);
$subSelect = $select->from('relocationaction', array('vehicle', 'maxend' => 'MAX(relocationaction.end)'))
->group('vehicle');
$subSelectString = '(' . $subSelect->__toString() . ')';
$select ->from(
array('relocationaction'), array('id', 'date' => 'start', 'enddate' => 'end', 'return'),
array('co2' => $subSelectString)
)
->joinLeft('exhibitvehicle', 'exhibitvehicle.id = relocationaction.vehicle', array())
->where('co2.vehicle = relocationaction.vehicle')
->where('relocationaction.monitor = 1')
->where('relocationaction.return IS NULL')
->where('start <= ?', $start->get('yyyy-MM-dd'))
->where('relocationaction.end = co2.maxend');
Can anyone please give me a hint?
Thanks
Jesse
UPDATE
This is the result of the second expression (total rubbish)
SELECT `relocationaction`.`vehicle`,
MAX(relocationaction.end) AS `maxend`,
`relocationaction_2`.`id`,
`relocationaction_2`.`start` AS `date`,
`relocationaction_2`.`end` AS `enddate`,
`relocationaction_2`.`return`
FROM `relocationaction`
INNER JOIN `(
SELECT ``relocationaction``.``vehicle``,
MAX(relocationaction.end) AS ``maxend`` FROM ``relocationaction`` GROUP BY ``vehicle``)`.`relocationaction` AS `relocationaction_2`
LEFT JOIN `exhibitvehicle` ON exhibitvehicle.id = relocationaction.vehicle
WHERE (col2.vehicle = relocationaction.vehicle)
AND (relocationaction.monitor = 1)
AND (relocationaction.return IS NULL)
AND (start <= '2013-05-08')
AND (relocationaction.end = col2.maxend)
GROUP BY `vehicle`

Answer 1

If you use a string in from(), Zend_Db_Select will consider it to be a table name so it escapes it.
The solution is to wrap your subselect into a Zend_Db_Expr.
$tbl = $this->getDbTable();
$select = $tbl->select()->setIntegrityCheck(false);
$subSelect = $select->from('relocationaction', array('vehicle', 'maxend' => 'MAX(relocationaction.end)'))
->group('vehicle');
$subSelectString = '(' . $subSelect->__toString() . ')';
$select ->from(
array('relocationaction'), array('id', 'date' => 'start', 'enddate' => 'end', 'return'),
array('co2' => new Zend_Db_Expr($subSelectString))
)
->joinLeft('exhibitvehicle', 'exhibitvehicle.id = relocationaction.vehicle', array())
->where('co2.vehicle = relocationaction.vehicle')
->where('relocationaction.monitor = 1')
->where('relocationaction.return IS NULL')
->where('start <= ?', $start->get('yyyy-MM-dd'))
->where('relocationaction.end = co2.maxend');

Answer 2

Ok here we go. I tried hard to find a solution with Zend_Db_Table but failed big time. That's why I finally did it with PDO, as suggested by #user466764. Thanks for your help.
$tbl = $this->getDbTable();
$query = 'SELECT relocationaction.id,
relocationaction.vehicle,
relocationaction.start,
relocationaction.end,
relocationaction.return
FROM relocationaction
(SELECT vehicle, MAX(end) AS maxend
FROM relocationaction
GROUP BY vehicle) AS co2
WHERE co2.vehicle = relocationaction.vehicle
AND(relocationaction.monitor = 1)
AND (relocationaction.return IS NULL)
AND (start <= "' . $start->get('yyyy-MM-dd') . '")
AND relocationaction.end = co2.maxend';
$sth = $tbl->getAdapter()->prepare($query);
$sth->execute();
$entries = $sth->fetchAll();