how to fit complex mysql query into zf2 - zend-framework2

Question

i am unable to fit my query into zf2 query, i can fit simple join query but i can not write for more complex sub queries.
please help me to do this.
SELECT `created_date` FROM `salesmodule_discussed_topic` dt WHERE dt.`meeting_id` IN(
SELECT ma.`meeting_id` FROM `salesmodule_meeting_agent` ma WHERE ma.`agent_id`=30547
)
public function getLastmeetingdate() {
$select = new Select();
$select->from(array('dt' => 'salesmodule_discussed_topic'));
$select->columns(array('created_date'));
$select->where(array('ma.`agent_id` => 30547));
$resultSet = $this->tableGateway->selectWith($select);
return $resultSet->buffer();
}

Answer 1

The previous example is bad because has an sql injections. You need make a subquery using Select.
public function getLastmeetingdate() {
$subQuery = new Select();
$subQuery->from(array('ma' => 'salesmodule_meeting_agent'));
$subQuery->columns(array('meeting_id'));
$subQuery->where(array('ma.agent_id' => 30547));
$select = new Select();
$select->from(array('dt' => 'salesmodule_discussed_topic'));
$select->columns(array('created_date'));
$select->where->in('dt.meeting_id', $subQuery);
return $this->tableGateway->selectWith($select);
}

Answer 2

public function fetchAllSubQuery($id = '') {
$columns = array("*");
$where = "main_booking_id IN (SELECT
b1.`main_booking_id`
FROM
`booking_sector` b1
WHERE b1.`connected_booking_id` = '$id' OR b1.`main_booking_id` = '$id') ";
$resultSet = $this->tableGateway->select(function (Select $select) use ($where,$columns) {
$select->where($where);
$select->columns($columns);
});
$resultSet->buffer();
// $resultSet->next();
return $resultSet;
}