original_string: public function union($select = array(), $type = self::SQL_UNION)
      {
          if (!is_array($select)) {
              // require_once 'Zend/Db/Select/Exception.php';
              throw new Zend_Db_Select_Exception(
                  "union() only accepts an array of Zend_Db_Select instances of sql query strings."
              );
          }
  
          if (!in_array($type, self::$_unionTypes)) {
              // require_once 'Zend/Db/Select/Exception.php';
              throw new Zend_Db_Select_Exception("Invalid union type '{$type}'");
          }
  
          foreach ($select as $target) {
              $this->_parts[self::UNION][] = array($target, $type);
          }
  
          return $this;
      }
code: public function union($select = array(), $type = self::SQL_UNION)
      {
          if (!is_array($select)) {
              // require_once 'Zend/Db/Select/Exception.php';
              throw new Zend_Db_Select_Exception(
                  "union() only accepts an array of Zend_Db_Select instances of sql query strings."
              );
          }
  
          if (!in_array($type, self::$_unionTypes)) {
              // require_once 'Zend/Db/Select/Exception.php';
              throw new Zend_Db_Select_Exception("Invalid union type '{$type}'");
          }
  
          foreach ($select as $target) {
              $this->_parts[self::UNION][] = array($target, $type);
          }
  
          return $this;
      }
code_tokens: public function union ( $ select = array ( ) , $ type = self :: SQL_UNION ) { if ( ! is_array ( $ select ) ) { // require_once 'Zend/Db/Select/Exception.php'; throw new Zend_Db_Select_Exception ( "union() only accepts an array of Zend_Db_Select instances of sql query strings." ) ; } if ( ! in_array ( $ type , self :: $ _unionTypes ) ) { // require_once 'Zend/Db/Select/Exception.php'; throw new Zend_Db_Select_Exception ( "Invalid union type '{$type}'" ) ; } foreach ( $ select as $ target ) { $ this -> _parts [ self :: UNION ] [ ] = array ( $ target , $ type ) ; } return $ this ; }
docstring: Adds a UNION clause to the query.
  
  The first parameter has to be an array of Zend_Db_Select or
  sql query strings.
  
  <code>
  $sql1 = $db->select();
  $sql2 = "SELECT ...";
  $select = $db->select()
  ->union(array($sql1, $sql2))
  ->order("id");
  </code>
  
  @param  array $select Array of select clauses for the union.
  @return Zend_Db_Select This Zend_Db_Select object.
docstring_tokens: Adds a UNION clause to the query .