$wpdb select returns empty array

I am trying to query databse to get posts with meta_key equals meta_value but it returns empty array, while if i used get_posts i got required result, what is wrong with my code (I hooked it to footer to check)

global $wpdb;


$wpdb->show_errors( true );
$querystr = "
SELECT $wpdb->posts.*
FROM $wpdb->posts
LEFT JOIN $wpdb->postmeta ON ($wpdb->posts.ID = $wpdb->postmeta.post_id)
WHERE $wpdb->postmeta.meta_key = 'workshop_id'
AND $wpdb->postmeta.meta_value = '13465'
AND $wpdb->posts.post_status = 'publish'
AND $wpdb->posts.post_type = 'forum'
ORDER BY $wpdb->posts.ID ASC
";


$workshops = $wpdb->get_results($querystr, OBJECT);

print_r($workshops);

Using this:

$workshops = get_posts([
    'post_type'   => 'forum',
    'numberposts' => -1,
    'post_status' => 'publish',
    'meta_key'    => 'workshop_id',
    'meta_value'  =>  '13465',
]);

print_r($workshops);

i get:

 Array
 (
[0] => WP_Post Object
    (
        [ID] => 13562
        [post_author] => 1
        [post_date] => 2019-01-02 20:05:21
        [post_date_gmt] => 2019-01-02 17:05:21
        //And the rest of properties..
    )
 )

Update

I have tried the following query and it worked(Why the one with problem doesn't):

$workshops_query = $wpdb->get_results( 
    $wpdb->prepare( 
        "
        SELECT post_id FROM $wpdb->postmeta
         WHERE meta_key = %s
         AND meta_value = %s
        ",
            'workshop_id', '13465'
        )
, OBJECT);
foreach($workshops_query as $workshop_query){
    $workshops[] = $workshop_query->post_id;
}

And yes both of queries tends to return different results, but one of them works, why the other doesn't?