當沒有預定義父 ID 或子 ID 時，從 MySQL PHP 構建層次結構

Question

我正在使用 MySQL 5.7，所以了解通用表表達式不可用，但我試圖找到一種方法來基於基於列的輸入構建層次結構。

例如，我的表由以下內容組成......

地區	辦公室	人
區域 1	辦公室 1	員工 1
區域 1	辦公室 1	員工 2
區域 1	辦公室 2	員工 1
區域 2	辦公室 1	員工 1
區域 2	辦公室 2	員工 1
區域 2	辦公室 2	員工 2

https://dbfiddle.uk/?rdbms=mysql_5.7&fiddle=049349ecdbf3369026e009dcb08b3c14

最初我曾詢問（在另一個已關閉的問題中）關於如何使用動態生成的 ID 和 ParentID 來實現這一點的方向，但如果沒有大量的子查詢，這似乎是不可能的。 換一種方式思考，這可以在 PHP 中實現，而不是構建一個數組嗎？

假設來自數據庫的結果是按照表...

<?php

$dbResponse = array(
  array(
    "Region" => "Region 1",
    "Office" => "Office 1",
    "Employee" => "Employee 1"
  ),
  array(
    "Region" => "Region 1",
    "Office" => "Office 1",
    "Employee" => "Employee 2"
  ),
  array(
    "Region" => "Region 1",
    "Office" => "Office 2",
    "Employee" => "Employee 1"
  ),
  array(
    "Region" => "Region 2",
    "Office" => "Office 1",
    "Employee" => "Employee 1"
  ) 
); // etc. etc. ...........


// Transformation here

如何將其轉化為生產所需的 output？

$newOutput = array(
  array(
    "Item" => "Region 1",
    "Children" => array(
                    "Item" => "Office 1",
                    "Children" => array(
                                    "Item" => array("Employee 1", "Employee 2")
                                    )
                    ),
                    array(
                    "Item" => "Office 2",
                    "Children" => array(
                                    "Item" => array("Employee 1")
                                    )
                    ),
  ), 
  array(
    "Item" => "Region 2",
    "Children" => array(
                    "Item" => "Office 1",
                    "Children" => array(
                                    "Item" => array("Employee 1")
                                    )
                    )
  )  
);

Answer 1

將嵌套轉換為數組的最簡單方法是 -

$newOutput = [];

foreach ($dbResponse as $row) {
    $newOutput[$row['Region']][$row['Office']][] = $row['Employee'];
}

這看起來像 -

Array
(
    [Region 1] => Array
        (
            [Office 1] => Array
                (
                    [0] => Employee 1
                    [1] => Employee 2
                )

            [Office 2] => Array
                (
                    [0] => Employee 1
                )

        )

    [Region 2] => Array
        (
            [Office 1] => Array
                (
                    [0] => Employee 1
                )

            [Office 2] => Array
                (
                    [0] => Employee 1
                    [1] => Employee 2
                )

        )

)

但是，如果您確實需要實現問題中建議的結構，那么您可以執行以下操作 -

$newOutput2 = [];

// initialise 2 counters
$r = $o = 0;

$previousRow = null;

foreach($dbResponse as $row) {
    if (is_null($previousRow)) {
        // no counter manipulation required
    } elseif ($previousRow['Region'] == $row['Region'] && $previousRow['Office'] != $row['Office']) {
        $o++;
    } elseif ($previousRow['Region'] != $row['Region']) {
        $r++;
        $o = 0;
    }

    $newOutput2[$r]['Item'] = $row['Region'];
    $newOutput2[$r]['Children'][$o]['Item'] = $row['Office'];
    $newOutput2[$r]['Children'][$o]['Children']['Item'][] = $row['Employee'];

    $previousRow = $row;
}

這看起來像 -

Array
(
    [0] => Array
        (
            [Item] => Region 1
            [Children] => Array
                (
                    [0] => Array
                        (
                            [Item] => Office 1
                            [Children] => Array
                                (
                                    [Item] => Array
                                        (
                                            [0] => Employee 1
                                            [1] => Employee 2
                                        )

                                )

                        )

                    [1] => Array
                        (
                            [Item] => Office 2
                            [Children] => Array
                                (
                                    [Item] => Array
                                        (
                                            [0] => Employee 1
                                        )

                                )

                        )

                )

        )

    [1] => Array
        (
            [Item] => Region 2
            [Children] => Array
                (
                    [0] => Array
                        (
                            [Item] => Office 1
                            [Children] => Array
                                (
                                    [Item] => Array
                                        (
                                            [0] => Employee 1
                                        )

                                )

                        )

                    [1] => Array
                        (
                            [Item] => Office 2
                            [Children] => Array
                                (
                                    [Item] => Array
                                        (
                                            [0] => Employee 1
                                            [1] => Employee 2
                                        )

                                )

                        )

                )

        )

)