TP5.1 where in 用法

$tag = Db::name('tag');

//写法1：
$data = array();
$data['id'] = array('in','4');
$tag = $tag->where($data)->select();
 
//写法2：
$tag = $tag->where(array('id'=>array('in','4')))->select();
$tag = $tag->where(array('id'=>array('in',array('4'))))->select();