创建表和检查表退出在同一函数不工作在php codeigniter？

<?php
defined('BASEPATH') OR exit('No direct script access allowed');

class Migration_Create_table extends CI_Migration {

    public function up()
    {
        $this->dbforge->add_field('id');
        $this->dbforge->add_field([
            'name' => [
                'type' => 'VARCHAR',
                'constraint' => '100',
            ],
            'email' => [
                'type' => 'VARCHAR',
                'constraint' => '100',
            ],
        ]);
        $this->dbforge->create_table('users');
    }

    public function down()
    {
        $this->dbforge->drop_table('users');
    }
}

php index.php migrate

public function check_table_exists()
{
    $query = $this->db->get_where('information_schema.tables', [
        'table_schema' => 'your_database_name',
        'table_name' => 'your_table_name',
    ]);
    
    return $query->num_rows() > 0;  // 如果大于0，则表存在；否则表不存在
}

public function check_table_exists()
{
    $sql = "SELECT 1 FROM information_schema.tables WHERE table_schema = 'your_database_name' AND table_name = 'your_table_name' LIMIT 1";
    $query = $this->db->query($sql);
    
    return $query->num_rows() > 0;  // 如果大于0，则表存在；否则表不存在
}