Union of two tables in Zend 2

I want to union two tables with where clause in zf2:-

table1 app_followers
table2 app_users
where condition could be anything
and order by updated_date.

Please let me know the query for zend 2.

Thanks..

Using UNION is ZF2:

Using ZF2 dedicated class Combine Zend\Db\Sql\Combine

    new Combine(
     [
      $select1,
      $select2,
      $select3,
       ...
     ]
    )

A detailed example which uses combine is as follows:

$select1 = $sql->select('java');
$select2 = $sql->select('dotnet');
$select1->combine($select2);

$select3 = $sql->select('android');

$selectall3 = $sql->select();
$selectall3->from(array('sel1and2' => $select1));
$selectall3->combine($select3);

$select4 = $sql->select('network');

$selectall4 = $sql->select();
$selectall4->from(array('sel1and2and3' => $selectall3));
$selectall4->combine($select4);

$select5 = $sql->select('dmining');

$selectall5 = $sql->select();
$selectall5->from(array('sel1and2and3and4' => $selectall4));
$selectall5->combine($select5);

which is equivalent to the normal SQL query for UNION:

SELECT * FROM java 
UNION SELECT * from dotnet 
UNION SELECT * from android 
UNION SELECT * from network;
UNION SELECT * from dmining;

I hope it helps.