有没有办法从表＃2获取数据，如果它有一个表＃1的外键，我会查询表＃1

Question

I have 2 tables, one called users and there is table called role_id, which gets data from second table called roles using foreign key. So role_id is an id of role but I want to get the value, which is located in roles table and print it instead of id. I don't even have a clue how to do it. So if we look at the code: I want to echo value of the role instead of role_id, but it is located in another table

$querytable = mysqli_query($con, "SELECT * from users WHERE role_id = '2' OR role_id = '1'");
        while($row=$querytable->fetch_assoc()):?>
         <tr><td><?php echo $row['username'];?></td>
         <td><?php echo $row['fio'];?></td>
         <td><?php echo $row['password'];?></td>
         <td><?php echo $row['role_id'];?></td>
         <td><?php echo $row['salary_fix'];?></td>
         <td><?php echo $row['salary_percent'];?></td></tr>
        <?php endwhile;?>

Answer 1

You can use JOIN for fetch data from linked tables

like that:

SELECT * from users 
JOIN roles ON users.role_id = roles.id
WHERE role_id IN (1, 2) 

and then you will have the values from the table roles for each user

check the docs for more information

https://dev.mysql.com/doc/refman/8.0/en/join.html