app-api/app/Models/Course/Cate.php

<?php

namespace App\Models\Course;

use Carbon\Carbon;
use Illuminate\Database\Eloquent\Model;
use DateTimeInterface;

class Cate extends Model
{
    protected $connection = 'mysql_c';
    protected $table='cate';
    protected $guarded=[];
    protected function serializeDate(DateTimeInterface $date): string
    {
        return $date->format('Y-m-d H:i:s');
    }
    public function getCreatedAtAttribute($value){
        return Carbon::createFromFormat('Y-m-d H:i:s', $value)->diffForHumans();
    }
    public function course(){
        return $this->hasMany(Course::class,'c_id','id');
    }

}