Laravel 5.2 - 左加入 DB::Raw 不起作用? [英] Laravel 5.2 - Left Join DB::Raw not working?

问题描述

我有以下查询，我尝试使用 DB::Raw() 进行左连接，但出现错误:

I have the following query where I'm trying to use DB::Raw() for the left join but I'm getting error:

IlluminateDatabaseQueryBuilder::leftJoin() 缺少参数 2

Missing argument 2 for IlluminateDatabaseQueryBuilder::leftJoin()

这是我的查询:

return $this->model->from('alerts as a')
    ->leftJoin(DB::Raw("locations as l on l.id = JSON_UNQUOTE(JSON_EXTRACT(a.criteria, '$.locationId'))"))
    ->leftJoin(DB::Raw("industries as i on find_in_set(i.id, JSON_UNQUOTE(JSON_EXTRACT(a.criteria, '$.industries')))"))
    ->where('user_id', '=', $userId)
    ->selectRaw("a.id
        , a.name
        , a.criteria
        , GROUP_CONCAT(DISTINCT(i.name) SEPARATOR ', ') as 'Industries'
            ->groupBy('a.id')
            ->orderBy('a.created_at', 'desc');

推荐答案

leftJoin 函数声明如下:

 public function leftJoin($table, $first, $operator = null, $second = null)

您想将原始函数作为第二列传入:

You want to pass your raw functions in as the second column:

return $this->model->from('alerts as a')
                   ->leftJoin('locations AS l', 'l.id', '=', DB::Raw("JSON_UNQUOTE(JSON_EXTRACT(a.criteria, '$.locationId'))"))
                   ->leftJoin('industries as i', function($join){
                        $join->on(DB::raw("find_in_set(i.id, JSON_UNQUOTE(JSON_EXTRACT(a.criteria,  '$.industries')))",DB::raw(''),DB::raw(''))); 
                   })

                   ->where('user_id', '=', $userId)
                   ->selectRaw("a.id
                             , a.name
                             , a.criteria
                             , GROUP_CONCAT(DISTINCT(i.name) SEPARATOR ', ') as 'Industries'")
                   ->groupBy('a.id')
                   ->orderBy('a.created_at', 'desc');

find_in_set 建议来自这里.

The find_in_set suggestion came from here.

我不确定 '$.locationId' 是什么，但如果它是一个变量，你可以将它作为一个数组中的参数作为 DB 上的第二个参数传递::raw() 函数.

I'm not sure what '$.locationId' is, but if it's a variable, you can pass that along as a parameter within an array as the second parameter on the DB::raw() function.

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