public function del(){
$ids=array(1,3,43);
$maps=array();
$maps['id'] = array('in',$ids);
D('Menu')->where($maps)->select();
echo M('Menu')->getLastSql();
echo "<br>";
exit;
}


<form name="form2" action="{:U('del')}" method="post">
<input type="checkbox" name="id[]" value="1" >
<input type="checkbox" name="id[]" value="2" >
<input type="checkbox" name="id[]" value="3" >
<input type="submit" name="submit" vlaue="提交">
</form>
提交到方法后结果是

SELECT * FROM `dm_menu` WHERE `id` = 'Array'

直接http://zhizu/index.php?s=/Admin/Menu/del.html 返回结果是

SELECT * FROM `dm_menu` WHERE `id` IN (1,3,43)