fuel/fuel/core/classes/database/query/builder/update.php
public function on($c1, $op, $c2)
	{
		$this->_last_join->on($c1, $op, $c2);

		return $this;
	}
public function on($c1, $op, $c2)
	{
		$this->_last_join->on($c1, $op, $c2);

		return $this;
	}
public function on ( $ c1 , $ op , $ c2 ) { $ this -> _last_join -> on ( $ c1 , $ op , $ c2 ) ; return $ this ; }
Adds "ON ..." conditions for the last created JOIN statement.

@param   mixed  $c1 column name or array($column, $alias) or object
@param   string $op logic operator
@param   mixed  $c2 column name or array($column, $alias) or object

@return  $this
Adds ON ... conditions for the last created JOIN statement .