在php mysql Zend框架中搜索多个值和多个字段

Here, I have three multi-select combo boxes namely department, designation and Location where the user can select more than one value in each field. I perform an OR operation in the query to display the name of the employee who belongs atleast one of the fields.

This works well if I choose only one department name, designation name and location. If I select more than 1 value,it dosent work. I have to for-loop the WHERE condition of department, designation and location based on the selected count.
How could I loop only the conditon here so that it becomes select 'emp_id' from emp_personal' where Department_Id='1' or Department_Id='7' or Designation_Id='6'....

public function listEmployees($searchArray=null, $logEmpId=null,  $formName=null) 
{

$department = $searchArray['Department'];
$designation= $searchArray['Designation'];
$location=$searchArray['Location'];


      $conditions=$this->_db->quoteInto('Department_Id =?', $department);  
      $conditions .= $this->_db->quoteInto('or Designation_Id = ?', $designation);
      $conditions .= $this->_db->quoteInto('or Location_Id = ?', $location);
      $qryEmployees= $this->_db->select()->from(array('En'=>$this->_ehrTables->empJob), array('En.Employee_Id'))->where($conditions)

     ->joinInner(array('E'=>$this->_ehrTables->empPersonal), 'E.Employee_Id = En.Employee_Id', array('Employee_Name'=>new Zend_Db_Expr("CONCAT(E.Emp_First_Name, ' ', E.Emp_Last_Name)")));



 $result = $this->_db->fetchAll($qryEmployees); 
 return $result;


}     

Try to use SELECT IN(value1,value2,...)