为什么在第一个foreach循环后我的变量数据被丢弃？

我正在使用CodeIgniter在数据库中插入记录。一切工作正常，但我似乎无法理解为什么嵌套数组的值在第一个foreach循环后会丢失其值。

的PHP

// $data is all data (array) passed from controller method.
public function create($data)
{
    $my_data = array(
        'name' => $data['name'],
        ....
    );

    if ($this->db->insert('myTable', $my_data)) {
        $insert_id = $this->db->insert_id();

        // $data['mySecondCheckbox'] has value here

        foreach ($first_data['myFirstCheckbox'] as $cb1) {
            $first_data = array(
                'fk_foo_id' => $insert_id,
                'fk_cb_id' => $cb1
            );

            $this->db->insert('mySecondTable', $first_data);
        }

        // $data['mySecondCheckbox'] has no value here

         foreach ($data['mySecondCheckbox'] as $cb2) {
            $second_data = array(
                'fk_foo_id' => $insert_id,
                'fk_cb_id' => $cb2
            );

            $this->db->insert('myThirdTable', $second_data);
        }

        return $insert_id;
    } else {
        return false;
    }

}

解决方案

谢谢@约翰！睡觉后很明显。当时，我以为$ data特定于每个each范围。

的PHP

// $data is all data (array) passed from controller method.
public function create($data)
{
    $my_data = array(
        'name' => $data['name'],
        ....
    );

    if ($this->db->insert('myTable', $my_data)) {
        $insert_id = $this->db->insert_id();

        // $data['mySecondCheckbox'] has value here

        foreach ($data['myFirstCheckbox'] as $cb1) {
            $first_data = array(
                'fk_foo_id' => $insert_id,
                'fk_cb_id' => $cb1
            );

            $this->db->insert('mySecondTable', $first_data);
        }

        // $data['mySecondCheckbox'] has no value here

         foreach ($second_data['mySecondCheckbox'] as $cb2) {
            $data = array(
                'fk_foo_id' => $insert_id,
                'fk_cb_id' => $cb2
            );

            $this->db->insert('myThirdTable', $second_data);
        }

        return $insert_id;
    } else {
        return false;
    }

}