How do i translate my SQL query to a Laravel Query

I'll assume you have two models setup : CanvasTopic and CanvasPostsTopic (based on Laravel table name conventions).

In your query you are have a implicit join, by listing both tables in the FROM clause and later filtering their relationship in the WHERE clause.

But the WHERE filter seems to filter by the relationship constraint, and the only column from canvas_posts_topics you retrieve is the foregin key.

Depending on the records on both tables the query above will yield a lot of duplicated records, as the other columns are from the derived table.

From my understanding you could simplify the query to this:

SELECT id, name FROM canvas_topics

Or, if you need the "duplicated" id column

SELECT id AS topic_id, id, name FROM canvas_topics

Note that I say "duplicated", because due to the WHERE condition all the records would have the same value for t.topic_id and ti.id

This simplified query could be translated to Eloquent as:

$records = CanvasTopic::get(['id', 'name']);

Or with the duplicated column:

$records = CanvasTopic::select(DB::raw('id AS topic_id'), 'id', 'name'])->get();

Where DB is the DB façade (\Illuminate\Support\Facades\DB).

If you need to perform the join anyhow you can try this:

$records = CanvasTopic::select([
            DB::raw('canvas_posts_topics.topic_id'),
            'canvas_topics.id',
            'canvas_topics.name',
        ])
        ->join('canvas_posts_topics', 'canvas_posts_topics.topic_id', '=', 'canvas_topics.id')
        ->get();

Or if you want to stick with the implicit join:

$records = CanvasTopic::select([
            DB::raw('canvas_posts_topics.topic_id'),
            'canvas_topics.id',
            'canvas_topics.name',
        ])
        ->from(DB::raw('canvas_posts_topics, canvas_topics')
        ->whereColumn('canvas_posts_topics.topic_id', 'canvas_topics.id')
        ->get();

If you find too much code, there is a not weel knowm method that let you populate a model from a raw query:

$records = CanvasTopic::fromQuery('SELECT t.topic_id, ti.id, ti.name FROM canvas_posts_topics AS t, canvas_topics AS ti WHERE t.topic_id = ti.id');

This is useful when you have a quite complex query

The thing is that i don't have different models for them, i'm trying to access and manipulate them directly from the database

Before doing that, actually work some of the examples in the docs, like:

$flight = App\Flight::where('active', 1)->first();

I usually write an eloquent query, not your data, but an example:

$quy = Powner::query()->leftJoin('dc_pets', 'dc_powners.ownerid', '=', 'dc_pets.ownerid')
                ->select('dc_powners.ownerid', 'dc_powners.oname')
                ->selectRaw('count(dc_pets.petid) as countOfPets')
                ->groupby('dc_powners.ownerid')
                ->orderby('dc_powners.oname')
                ->get();

Results basically give:

ownerid, oname, countOfPets

Like:

5|Bob|3
4|Greg|9
2|Rob|1

A little trial and error is required. But learn first, work some of those examples in the docs, otherwise every query you need will have to be translated for you.