Laravel 为什么查询返回空集合?
我知道以下查询是由Laravel创建的:Laravel 为什么查询返回空集合?,laravel,laravel-5,laravel-5.2,laravel-5.3,Laravel,Laravel 5,Laravel 5.2,Laravel 5.3,我知道以下查询是由Laravel创建的: $res = Announcement::whereExists(function ($query) { $query->select(DB::raw(1)) ->from('announcement_category')->join('user_category', 'user_category.category_id', '=', 'announcement_c
$res = Announcement::whereExists(function ($query) {
$query->select(DB::raw(1))
->from('announcement_category')->join('user_category', 'user_category.category_id', '=', 'announcement_category.category_id')
->where('user_category.user_id', '=', 1)
->where('announcement_category.announcement_id', '=', 'announcements.id');
});
dd($res->get());
上面的代码给了我一个空集合:dd($res->get())代码>
此查询的纯SQL代码为:
select * from `announcements` where exists (select 1 from
`announcement_category` inner join `user_category` on
`user_category`.`category_id` = `announcement_category`.`category_id` where `user_category`.`user_id` = 1
and `announcement_category`.`announcement_id` = announcements.id)
and `announcements`.`deleted_at` is null
如果直接在MySQL中执行,我将得到两个结果行
但是为什么dd($res->get())代码>将我重新整理为空?我认为雄辩的模型中不存在一个存在的地方。。。试试这个:
$res = DB::table('announcement')->whereExists(function ($query) {
$query->select(DB::raw(1))
->from('announcement_category')->join('user_category', 'user_category.category_id', '=', 'announcement_category.category_id')
->where('user_category.user_id', '=', 1)
->where('announcement_category.announcement_id', '=', 'announcements.id');
})->get();
为什么在SELECT子句中使用DB::raw(1)
?如果使用*
结果相同,则为: