PHP递归实现无限分类

1.表结构

2.展示效果

[
    {
        "id": "1", 
        "name": "中国", 
        "parent": "0", 
        "child": [
            {
                "id": "2", 
                "name": "江苏", 
                "parent": "1", 
                "child": [
                    {
                        "id": "3", 
                        "name": "苏州", 
                        "parent": "2", 
                        "child": [
                            {
                                "id": "4", 
                                "name": "昆山", 
                                "parent": "3"
                            }
                        ]
                    }
                ]
            }
        ]
    }, 
    {
        "id": "5", 
        "name": "美国", 
        "parent": "0", 
        "child": [
            {
                "id": "6", 
                "name": "加利福尼亚", 
                "parent": "5", 
                "child": [
                    {
                        "id": "7", 
                        "name": "洛杉矶", 
                        "parent": "6"
                    }
                ]
            }
        ]
    }
]

3.代码实现

<?php
$sql = "SELECT id, name, parent FROM YourTable";
$countrys = $conn->query($sql);

// 第一次查询，找出根节点
foreach ($countrys as $curr){
    if($curr['parent'] == 0){
      $r[] = $this->child($curr,$countrys);
    }
}

// 查询当前节点的子节点
function child($curr,$countrys){
    foreach ($countrys as $key => $country){
        if($curr['id'] == $country['parent']){
            $curr['child'][] = child($country,$countrys);
        }
    }
    return $curr;
}

echo json_encode($r);
#结果
#[{"id":"1","name":"\u4e2d\u56fd","parent":"0","child":[{"id":"2","name":"\u6c5f\u82cf","parent":"1","child":[{"id":"3","name":"\u82cf\u5dde","parent":"2","child":[{"id":"4","name":"\u6606\u5c71","parent":"3"}]}]}]},{"id":"5","name":"\u7f8e\u56fd","parent":"0","child":[{"id":"6","name":"\u52a0\u5229\u798f\u5c3c\u4e9a","parent":"5","child":[{"id":"7","name":"\u6d1b\u6749\u77f6","parent":"6"}]}]}]

小结：这种小功能可用于菜单、类型的查询，在项目中可以用缓存保存