adding UNION support (#2549)

classes/kohana/database/query/builder/select.php

@@ -36,6 +36,9 @@ class Kohana_Database_Query_Builder_Select extends Database_Query_Builder_Where
 	// OFFSET ...
 	protected $_offset = NULL;
 
+    // UNION ...
+    protected $_union = array();
+
 	// The last JOIN statement created
 	protected $_last_join;
 
@@ -298,6 +301,26 @@ public function limit($number)
 		return $this;
 	}
 
+	/**
+	 * Adds an other UNION clause.
+	 * 
+	 * @param mixed $select if string, it must be the name of a table. Else
+	 *  must be an instance of Database_Query_Builder_Select
+	 * @param boolean $all decides if it's an UNION or UNION ALL clause
+	 * @return $this
+	 */
+	public function union($select, $all = TRUE)
+	{
+		if (is_string($select))
+		{
+			$select = DB::select()->from($select);
+		}
+		if ( ! $select instanceof Database_Query_Builder_Select)
+			throw new Kohana_Exception('first parameter must be a string or an instance of Database_Query_Builder_Select');
+		$this->_union []= array('select' => $select, 'all' => $all);
+		return $this;
+	}	
+
 	/**
 	 * Start returning results after "OFFSET ..."
 	 *
@@ -392,6 +415,18 @@ public function compile(Database $db)
 			// Add offsets
 			$query .= ' OFFSET '.$this->_offset;
 		}
+
+		if ( ! empty($this->_union))
+		{
+			foreach ($this->_union as $u) {
+				$query .= ' UNION ';
+				if ($u['all'] === TRUE)
+				{
+					$query .= 'ALL ';
+				}
+				$query .= $u['select']->compile($db);
+			}
+		}
 
 		return $query;
 	}
@@ -404,7 +439,8 @@ public function reset()
 		$this->_where    =
 		$this->_group_by =
 		$this->_having   =
-		$this->_order_by = array();
+		$this->_order_by =
+		$this->_union = array();
 
 		$this->_distinct = FALSE;
 
@@ -416,3 +452,4 @@ public function reset()
 	}
 
 } // End Database_Query_Select
+