使用Laravel的Eloquent，你可以使用模型关系来简化。我假设您已经为每个表定义了Eloquent模型。

use App\Models\Category;

$categories = Category::with('tags')->get();

$result = [];

foreach ($categories as $category) {
    $result[$category->name] = $category->tags->pluck('name')->toArray();
}

不要忘记在类别模型中定义关系

namespace App\Models;

use Illuminate\Database\Eloquent\Model;

class Category extends Model
{
    public function tags()
    {
        return $this->hasMany(Tag::class);
    }
}

在Tag模型中

namespace App\Models;

use Illuminate\Database\Eloquent\Model;

class Tag extends Model
{
    public function category()
    {
        return $this->belongsTo(Category::class);
    }
}