Zend Framework Select Objects And UNION() - php

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

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 2

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 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')

Answer 4

This practical example shows a function that returns a rowset of either latest or if a available favourite blog entries of a specific year (artwork blog):
public function fetchBestOf($year)
{
$selectLatest = $this->select()->where('isHidden = 0')
->where('YEAR(dateCreated) = ' . $year)
->where('isHighlight = 0');
$selectHighlights = $this->select()->where('isHidden = 0')
->where('YEAR(dateCreated) = ' . $year)
->where('isHighlight = 1');
$selectUnion = $this->select()->union(array($selectLatest, $selectHighlights), Zend_Db_Select::SQL_UNION_ALL)
->order('isHighlight DESC')
->order('dateCreated DESC')
->order('workID DESC')
->limit('5');
$rowset = $this->fetchAll($selectUnion);
return $rowset;
}

Answer 5

The best way Zend suggest is like follows....
$sql = $this->_db->select()
->union(array($select1, $select2,$select3))
->order('by_someorder');
echo $sql->__toString();
$stmt = $db->query($sql);
$result = $stmt->fetchAll();
echo will show the query
Here $select1, $select2, $select3 can be different select queries with same
number of columns...

Answer 6

This is how it works for me:
$select1 = $this->select();
$select2 = $this->select();
After getting the necessary data in both queries the UNION syntax goes like this:
$select = $this->select()->union(array('('.$select1.')', '('.$select2.')'));