如何通过 laravel 中的查询生成器获取数据答案

【问题标题】：How to get data by query builder in laravel如何通过 laravel 中的查询生成器获取数据
【发布时间】：2021-03-25 12:59:48
【问题描述】：

我在查询生成器中使用连接，这是输出

[
    {
        "id": 7,
        "name": "class 1",
        "idSubject": 17,
        "nameSubject": "Math"
    },
    {
        "id": 7,
        "name": "class 1",
        "idSubject": 16,
        "nameSubject": "history"
    },
    {
        "id": 8,
        "name": "class 2",
        "idSubject": 15,
        "nameSubject": "Computer"
    },
    {
        "id": 8,
        "name": "class 2",
        "idSubject": 19,
        "nameSubject": "geography"
    }
]

您可以看到 1、2 类的 id 和 name 出现了两次。那么，如何让它出现一次呢。

这是我的查询：

    $data = DB::table('class')->join('class_subject','class.id','=','class_subject.class_id')
 ->join('subject','class_subject.subject_id','=','subject.id') 
->select('class.id','class.name','subject.id as idSubject','subject.name as nameSubject') ->get();

我想要它：

[
    {
        "id": 7,
        "name": "class 1",
        "subject": [{"idSubject":"17","nameSubject: "Math"},
                    {"idSubject":"16","nameSubject: "history"}]
    }
]

【问题讨论】：

$data = DB::table('class')->join('class_subject','class.id','=','class_subject.class_id') ->join('subject ','class_subject.subject_id','=','subject.id') ->select('class.id','class.name','subject.id as idSubject','subject.name as nameSubject') ->get();

标签： laravel laravel-5 eloquent

【解决方案1】：

distinct 方法允许您强制查询返回不同的结果：

试试这个

$data = DB::table('class')->join('class_subject','class.id','=','class_subject.class_id')
 ->join('subject','class_subject.subject_id','=','subject.id') 
->select('class.id','class.name','subject.id as idSubject','subject.name as nameSubject')->distinct()->get();

【讨论】：