php - Mysql 一个父多个子结果不重复父行

Question

我正在使用 Codeigniter 和 MYSQL 构建 CMS。并有一个像这样的表。

CREATE TABLE parent
(`parentId` int, `parentName` varchar(50));

INSERT INTO parent
(`parentId`, `parentName`)
VALUES
(1, 'Movie'),
(2, 'Food'),
(3, 'Sports');

CREATE TABLE child
(`childId` int, `parentId` int,`childName` varchar(50));
INSERT INTO child
(`childId`, `parentId`, `childName`)
VALUES
(1, 1, 'Harry Potter'),
(2, 3, 'Foot Ball'),
(3, 2, 'Pizza'),
(4, 2, 'Burger'),
(5, 1, 'Avengers'),
(6, 1, 'Fury'),
(7, 3, 'Cycling');

并希望输出像这样打印输出

foreach($parent as $parentData):
echo"<h4>".$parentData->parentName."</h4>";
echo"<ul>";
 foreach($child as childData):
 echo"<li>".$childData->childName."</li>";
 endforeach;
echo"</ul>"
endforeach;

产生这个

<h4>Movie</h4>
<ul>
<li>Harry Potter</li>
<li>Avengers</li>
<li>Fury</li>
</ul>
<h4>Food</h4>
<ul>
<li>Pizza</li>
<li>Burger</li>
</ul>
<h4>Sports</h4>
<ul>
<li>Foot Ball</li>
<li>Cycling</li>
</ul>

欢迎对代码进行任何调整。 因为我过去几个小时一直在尝试这个。 提前致谢。

更新: 我按照 CodeGodie 的建议实现了代码的答案，并添加了这样的 View 。

foreach ($result as $arr) {
if (!isset($final[$arr["parentName"]])) {
    $final[$arr["parentName"]] = array();
}
array_push($final[$arr["parentName"]], $arr);
}
foreach ($final as $parent=> $childs) {
echo $parent."<br>";
foreach ($childs as $child) {
    print_r($child) ;
}
}

现在我得到了我期待的结果

Answer 1

有多种方法可以做到这一点。但是我会使用以下方法:

1. 您需要创建以下 SQL 查询:

   SELECT * FROM parent p
   JOIN child c ON c.parentId = p.parentId
   ORDER BY parentName
   

   或者在 Codeigniter 中:

   $this->db->select("*");
   $this->db->from("parent p");
   $this->db->join("child c", "c.parentId = p.parentId ");
   $this->db->order_by("parentName");
   $q = $this->db->get();
   return $q->result_array();
   

   这会给你这样的结果:

   $result = array(
       array(
          "parentId" => 2,
          "parentName" => "Food",
          "childId" => 3,
          "childName" => "Pizza",
       ),
       array(
          "parentId" => 2,
          "parentName" => "Food",
          "childId" => 4,
          "childName" => "Burger",
       ),
       array(
          "parentId" => 1,
          "parentName" => "Movie",
          "childId" => 1,
          "childName" => "Harry Potter",
       ),
       array(
          "parentId" => 1,
          "parentName" => "Movie",
          "childId" => 5,
          "childName" => "Avengers",
       )
   );
   

2. 迭代结果:

   foreach ($result as $arr) {
       if (!isset($final[$arr["parentName"]])) {
           $final[$arr["parentName"]] = array();
       }
       array_push($final[$arr["parentName"]], $arr);
   }
   
   var_dump($final);
   

   这会给你一个像这样的结果，然后你可以迭代它来构建你的 HTML:

   array (size=2)
     'Food' => 
       array (size=2)
         0 => 
           array (size=4)
             'parentId' => int 2
             'parentName' => string 'Food' (length=4)
             'childId' => int 3
             'childName' => string 'Pizza' (length=5)
         1 => 
           array (size=4)
             'parentId' => int 2
             'parentName' => string 'Food' (length=4)
             'childId' => int 4
             'childName' => string 'Burger' (length=6)
     'Movie' => 
       array (size=2)
         0 => 
           array (size=4)
             'parentId' => int 1
             'parentName' => string 'Movie' (length=5)
             'childId' => int 1
             'childName' => string 'Harry Potter' (length=12)
         1 => 
           array (size=4)
             'parentId' => int 1
             'parentName' => string 'Movie' (length=5)
             'childId' => int 5
             'childName' => string 'Avengers' (length=8)
   

希望这有帮助