使用子数组之一的索引访问所有其他子数组:

Use the indexes of one of the sub-arrays to access all the other sub-arrays:

foreach ($array['item_id'] as $i => $item_id) {
    $request_explanation = $array['request_explanation'][$i];
    $quantity = $array['quantity'][$i];
    // repeat this for all the columns
    // Now you can insert all these variables into the database
}