PHP / HTML使用两个表并获取在html表中使用的名称

i have a little problem, right now i'm making a little ticket system.

I have a table where it displayes available tickets created related to that user.

Example: User Nick has 3 tickets and it gets displayed like that.

+-----------+------------+---------+
| Ticket ID | Created by | Comment |
+-----------+------------+---------+
|     2     |     4      |  Text   | <- Ticket 1
+-----------+------------+---------+
|     3     |     2      |  Text   | <- Ticket 2
+-----------+------------+---------+
|     5     |     3      |  Text   | <- Ticket 3
+-----------+------------+---------+

Right now, i have only the userid in the column 'created by' but i want the username to be displayed instead.

I have two database tables and all users are saved in table 1 and the tickets get saved in table 2, now I need a query to get the username of the userid 4,2,3 to display the username in the HTML table but i don't know how to do that.

My current query looks like this:

$pdo->query("BEGIN");
$t = ("SELECT * FROM ticket WHERE uid='$param'");
$pdo->query("COMMIT");

To explane the 'uid', with the uid i get the tickets related to that player.

//Edit

That is not exactly that what i'm searching for, maybe i explained it a little bit wrong.

This is my ticket table: Ticket Table

First row: Ticket ID Second row: The UID identifes the user the ticket got created for Third row: the ID of the user that created the ticket.

Now i have the user table: User Table

First row: Identifes the user Third row: Is the username of the user

Now i have a html table(That's just a small part of the table): HTML Table

First row: The userid of the user created that ticket Second row: The ticket ID

Right now it displays all the tickets created for UID 76561198073236987 and instead of displaying only the ID of the user created the ticket i want to display the username.

I solved this on my own with following Query.

SELECT ticket.*, users.benutzername FROM ticket INNER JOIN users ON ticket.created_by=users.id WHERE uid='$param'

In this example i replaced all my results with a "*" to make this query shorter.

Use SQL Joints. See below query

"SELECT * FROM ticket
LEFT JOIN user ON user.uid= ticket.uid WHERE ticket.uid='$param'";

This will return user details alongside with ticket details.
ticket details will be received either user is available or not
For more about left join :https://www.w3schools.com/sql/sql_join_left.asp

If you want only the tickets which has user details, You can user inner-join or join. See below query

"SELECT * FROM ticket
    INNER JOIN user ON user.uid= ticket.uid WHERE ticket.uid='$param'";

This will return user details alongside with ticket details.
ticket details will not be received if user is not available
For more about Inner join :https://www.w3schools.com/sql/sql_join_inner.asp