Mysql 嵌套并声明为数组

Question

我有 2 个 table 想要调用并从中创建另一个数组。第一个 table 是 groups

| id |  name   | type |
  1    premium    pr
  2    basic      bs

第二个table是子组

| id |  group_id   |    name   |
  1        1          forever
  2        2          short

其实我想展示这样的代码。将另一个数组函数声明为子组

Array ( 
[id] => 1 
[name] => Premium 
[type] => pr 

)[sub-groups] => Array (
[0] => Array (
[id] => 1
[group_id] => 1
[name] => forever))

我创建了这个 PDO sql 连接

=================编辑代码====================

function getGroups(){
    global $conn;
    $stmt = $conn->prepare("SELECT * FROM groups");
    $stmt->execute();
    $stmt->setFetchMode(PDO::FETCH_ASSOC);
    $groups = $stmt->fetchAll();
    foreach($groups as $key => $val){

        $stmt = $conn->prepare("SELECT * FROM sub_groups WHERE group_id = {$val['id']}");
        $stmt->execute();
        $stmt->setFetchMode(PDO::FETCH_ASSOC);
        $program = $stmt->fetchAll();
        foreach($program as $key => $val){
            $groups['sub-groups'] = $program;
        }
    }
    return $groups;
}

代码成功显示了高级组和基本组，但没有显示主组内的子组。我错过了什么？任何有帮助的人都会很好。

Answer 1

数组键必须是唯一的。如果您有两列同名，则只有其中一列可以出现在行的结果关联数组中。

您需要为至少一个具有相同名称的列分配一个别名，以便它在结果中显示不同。

SELECT g.name as group_name, sg.group_id, sg.id AS subgroup_id, sg.name AS subgroup_name
FROM groups AS g
LEFT JOIN subgroups AS sg ON sg.group_id = g.id

当您创建 PHP 结果时，$groups['sub-groups'] 需要是一个数组。每次循环都用一个元素覆盖它。

<?php
function getGroups(){
    global $conn;
    $groups = [];
    $stmt = $conn->prepare("
                SELECT g.name as group_name, sg.group_id, sg.id AS subgroup_id, sg.name AS subgroup_name
                FROM groups AS g
                LEFT JOIN subgroups AS sg ON sg.group_id = g.id");
    $stmt->execute();
    $stmt->setFetchMode(PDO::FETCH_ASSOC);
    while ($row = $stmt->fetch()){
        if (!isset($groups[$row['group_name']])) {
            $groups[$row['group_name']] = $row;
            $groups[$row['group_name']]['sub-groups'] = [$row['subgroup_name']];
        } else {
            $groups[$row['group_name']]['sub-groups'][] = $row['subgroup_name'];
        }
    }
    return $groups;
}

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