Laravel不存在的地方 [英] Where not Exists en Laravel

问题描述

有人可以告诉我我的laravel查询中可能有什么错误，基本上我想要列出的是ID与另一个表无关的表的记录.我使用以下查询在Mysql中完成了此操作:SELECT * FROM不存在的项目(SELECT等级为空，而grades.item_id = item.id和qualifications.user_id = 2)

但是现在我需要在laravel中执行相同的查询，我以这种方式尝试了它: codigo

我得到的是这个语法错误，我不知道该如何解决了:错误

我非常感谢能告诉我我做错了什么，或者我在Laravel中以哪种形式进行查询的人.

解决方案

您也可以像

一样将查询重写为左连接

  SELECT i.*从项目我左联接资格q ON q.item_id = i.id AND q.user_id = 2q.item_id为NULL的位置 

在查询构建器中，您可以将其编写为

  DB :: table('item as i')->选择('i.*')-> leftJoin('qualification as q'，qualities as q'，function($ join)use($ user_id){$ join-> on('q.item_id'，'='，'i.id')-> on('q.user_id'，'='，$ user_id);})-> whereNull('q.item_id')-> get(); 

我建议您使用的另一种方法是建立关系和模型，并雄辩地做到这一点

  class项目扩展模型{公共职能资格{返回$ this-> hasMany(\ App \ Models \ Qualification :: class，'item_id');}}班级资格扩展模型{公共职能资格{返回$ this-> belongsTo(Item :: class，'item_id');}} 

然后您可以使用查询关系缺失

  Item :: whereDoesntHave('qualifications'，function($ query)use($ user_id){$ query-> where('user_id'，'='，$ user_id);})-> get(); 

Could anybody tell me what error I might have in my laravel query, basically what I want is to list the records of a table whose id is not related in another table. I did it in Mysql with this query: SELECT * FROM item WHERE NOT EXISTS (SELECT null FROM qualifications WHERE grades.item_id = item.id AND qualifications.user_id = 2);

but now I need to do this same query in laravel, I tried it this way: codigo

and what I get is this syntax error that I do not know how to solve anymore: error

I am very grateful to anyone who can tell me what I am doing wrong, or in what form I make that query in Laravel.

解决方案

You can also rewrite your query as left join like

SELECT i.*
FROM item i
LEFT JOIN qualifications q ON q.item_id = i.id  AND q.user_id = 2
WHERE q.item_id IS NULL

In query builder you can write it as

DB::table('item as i')
    ->select('i.*')
    ->leftJoin('qualifications as q', function ($join) use($user_id) {
        $join->on('q.item_id', '=', 'i.id')
             ->on('q.user_id', '=', $user_id);
    })
    ->whereNull('q.item_id')
    ->get();

Another approach which i suggest you to go with, is setup your relations and models and do it with eloquent way

class Item extends Model
{
    public function qualifications()
    {
        return $this->hasMany(\App\Models\Qualification::class, 'item_id');
    }
}

class Qualification extends Model
{
    public function qualifications()
    {
        return $this->belongsTo(Item::class, 'item_id');
    }
}

And then you can use Querying Relationship Absence

Item::whereDoesntHave('qualifications', function ($query) use($user_id) {
    $query->where('user_id', '=', $user_id);
})->get();

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