Laravel -如何更新按其列计算的数据

php artisan make:migration update_column_data

use Illuminate\Support\Facades\Schema;
use Illuminate\Database\Schema\Blueprint;
use Illuminate\Database\Migrations\Migration;

class UpdateColumnData extends Migration
{
    public function up()
    {
        Schema::table('your_table_name', function (Blueprint $table) {
            $table->decimal('price', 8, 2)->change();
            $table->integer('quantity')->change();
            $table->decimal('total', 8, 2)->nullable()->default(0);
        });

        // 更新数据
        DB::table('your_table_name')->get()->each(function ($row) {
            $total = $row->price * $row->quantity;
            DB::table('your_table_name')->where('id', $row->id)->update(['total' => $total]);
        });
    }

    public function down()
    {
        Schema::table('your_table_name', function (Blueprint $table) {
            $table->dropColumn('total');
        });
    }
}