PHP数组对比与数据库查询方法

$array1 = ['a' => 1, 'b' => 2, 'c' => 3];
$array2 = ['a' => 1, 'b' => 4, 'd' => 5];

$result = array_diff_assoc($array1, $array2);
// 结果: ['b' => 2, 'c' => 3]，因为'b'值不同，'c'在$array2中不存在

$diff1 = array_diff_assoc($array1, $array2);
$diff2 = array_diff_assoc($array2, $array1);
$full_diff = array_merge($diff1, $diff2);

SELECT n.id, n.name, n.email
FROM users_new n
LEFT JOIN users_old o ON n.id = o.id
WHERE o.id IS NULL OR n.name != o.name OR n.email != o.email;

SELECT 'in_new_not_old' AS source, id FROM users_new WHERE id NOT IN (SELECT id FROM users_old)
UNION
SELECT 'in_old_not_new', id FROM users_old WHERE id NOT IN (SELECT id FROM users_new);

// 从数据库获取数据
$old_data = fetchFromDatabase('SELECT id, name, email FROM users_old');
$new_data = fetchFromDatabase('SELECT id, name, email FROM users_new');

// 转换为以id为键的关联数组
$old_map = array_column($old_data, null, 'id');
$new_map = array_column($new_data, null, 'id');

// 找出变更项
$changed = [];
foreach ($new_map as $id => $row) {
    if (!isset($old_map[$id])) {
        $changed[$id] = ['type' => 'added', 'data' => $row];
    } elseif ($old_map[$id] != $row) {
        $changed[$id] = [
            'type' => 'modified',
            'old' => $old_map[$id],
            'new' => $row
        ];
    }
}