php - 从两个表创建自定义 json 数组

Question

我在 mysql 中有下表。 1)用户

userid    username    college
1         robert      sarauniversity
2         albert      oxford

2)UserDetails
userid     subjectid
1          1
1          2
2          3
1          4
2          1

3)subjectdetails
subjectid  subjectname          subjectteacher
1          basic science        pro. vengaskar
2          advance mathematics  pro. richard
3          history              pro. michale
4          geography            pro. renuka

我需要以下 json 数据

  [  
  {
   id:1
   username:robert      
   subjects:[
   {
       subjectname:pro. geography            ,
       subject teacher:algebra

   },
  {
       subjectname:pro. vengaskar,
       subject teacher:pro. renuka
  }
  ]
  },
  {
   id:2
   username:albert      
   subjects:[
   {
       subjectname:history                          ,
       subject teacher: pro. michale

   },
  {
       subjectname:basic science,
       subject teacher: pro. vengaskar

  }
  ]
  }
  }

我已经开发过几次json Rest api，但这次是带有json数组的对象的json数组。 我很困惑如何迭代内容并获得最终所需的 json。 我不会粘贴 php 代码，因为没有任何帮助我。 很遗憾，我花了两天时间，但仍处于开始阶段......

Answer 1

通过这样的查询得到结果

SELECT A.userid,A.username, C.subjectname,C.subjectteacher FROM `A` AS users INNER JOIN `UserDetails` AS B on A.userid = b.userid INNER JOIN `subjectdetails` AS C on C.subjectid = B.subjectid

然后在循环中以以下格式操作结果

$arr = array (
        array (
                "id" => "1",
                "username" => "Robert",
                "subjects" => array (
                        array (
                                "subjectname" => "pro. geography",
                                "subject teacher" => "algebra" 
                        ) 
                ) 
        ) 
);

echo json_encode ( $arr );

输出

[
    {
        "id": "1",
        "username": "Robert",
        "subjects": [
            {
                "subjectname": "pro. geography",
                "subject teacher": "algebra"
            }
        ]
    }
]