swap_inner_handle()
$handle->swap_inner_handle($handle)
This method is used to swap handles. However, it’s better to
create new handles or use some other method within your program. Both
the handle that calls the method and the other handle given for the
parameter of this method must be of the same type and have the same
parent (i.e., $dbh is parent of both
$sth1 and $sth2).