如何从多个用户一起从两个不同的表中获取数据？

I have 1 table for the user, 1 for comments and another for friends below is the table structure :

Comments Table :

------------------------------------------------
| comment_id  | user_id_c | commentstatus      | 
------------------------------------------------
|  1          |   1       |   Sample comment 1 |
|  2          |   2       |   Sample comment 2 |
------------------------------------------------

User Table :

------------------------------------------------------
| id  | username            | password  |  Full name |
------------------------------------------------------
|  1  |   user1 (loggedin)  | Sample 1  |  John      |
|  2  |   user2             | Sample 2  |  Smith     |
|  3  |   user3             | Sample 3  |  Andrew    |
|  4  |   user4             | Sample 4  |  Victor    |
|  3  |   user5             | Sample 3  |  Robert    |  
-------------------------------------------------------

Friends Tables

---------------------------------------------------
| id  | friend1             | friend2   |   status   
---------------------------------------------------
|  1  |   user1             | user3     |  friend
|  2  |   user1             | user5     |  friend
|  3  |   user2             | user4     |  friend
---------------------------------------------------

currently, if any user posts a comment it gets inserted there in the database inside comments table. now if I am logged in I can fetch all my comments from the database.

To explain I would like to inform that you all can see, user 1 is friend with user 3 and user 5 according to the friends table.

All I want is to fetch the comments for the logged in user and for those who are the friend with the logged in user. however, I am unable to figure it out that how can I fetch the comments of loggedin user and it's friends all together.

the script I am using to fetch my posts is as follows :

public function comments(){
            global $pdo;
            $query = $pdo->prepare("SELECT u.*, c.* FROM users u INNER JOIN comments c ON u.id = c.user_id_c WHERE u.id = ".$_SESSION['sid']." ORDER BY c.comment_id DESC");
            $query->execute();
            return $query->fetchAll();
        }

and then fetching comments using below code :

$comments  = $get->comments();

Then :

foreach($comments as $row){

echo $row['Full name']; //user name from user table in the database
echo $row['commentstatus']; //comment from comments table in the database

It is fetching data for the logged in user perfectly, Is it possible anyway that I can fetch the comments from the friends of the logged in user also with logged in user's comments from the database at the same time.

You are looking for something like this:

$query = $pdo->prepare("SELECT u.*, c.* FROM users u INNER JOIN comments c ON u.id = c.user_id_c WHERE u.id = ".$_SESSION['sid']." OR c.user_id IN (SELECT friend_id FROM friends WHERE friends.user_id = ".$_SESSION['sid'].") ORDER BY c.comments_id DESC"