Zend Framework Select Objects And UNION()

Question

I'm pretty sure this is not possible in Zend Framework (I have searched the Web, the documentation and issue tracker) but I just want to make sure so I'm asking here.

$select = $this->select();
$select->union($select1, $select2);

That doesn't work of course. To explain what I need. I need to use UNION() to merge 2 tables in a SELECT query, I know I could just do:

$select = "$select1 UNION $select2";

The problem is that would return a string and I need to get a select object so I can use it with Zend_Paginator.

I have already solved the issue by modifying my database architecture but I'm just curious if there is some workaround for this.

Answer 1

Zend_Db_Select has a union method so I'd have thought it is possible, if you can build your query using a select object. I haven't used Zend_Db_Select (or the table subclass) with union but I'd imagine you can do something like

$select = $this->select()
               ->where('blah')
               ->union($sql);

Answer 2

Here's what I've done to make a union:

$select = $this->select();
//common select from both sides of the union goes here

$select1 = clone($select);
//select1 specifics here

$select2 = clone($select);
//select 2 specifics here

$db = $this->getAdapter();
$pageselect = $db->select()->union(array("($select1)", "($select2)"));

Remember Db_Select's __toString will print out the SQL generated by that select, to help you debug.

Answer 3

a complete example:

 public function getReservationById($id)
 {
  if(!$id) return null;

  $sql = $this->table->select();
  $sql->union(array(
   $this->table->select()->where('id=?', $id),
   $this->tableFinished->select()->where('id=?', $id),
   $this->tableCanceled->select()->where('id=?', $id),
   $this->tableTrashed->select()->where('id=?', $id)
   ));
  echo $sql->__toString();
 }

and the generated query:

SELECT reservations.* FROM reservations WHERE (id='5658') UNION SELECT res_finished.* FROM res_finished WHERE (id='5658') UNION SELECT res_cancel.* FROM res_cancel WHERE (id='5658') UNION SELECT res_trash.* FROM res_trash WHERE (id='5658')