How to allow mutilple page to insert multiple data at the same time (Will not clash) in mysql PHP

I have a online page which will allow user to create ac acoount for them inorder to acceess our page.

I worry in some period, there will be a lots of user who create at the same time. In that case, I worry my database will be clash or conflict.

Can i know is that anyway to prevent that happens ?

My table as below :

CREATE TABLE user ( id int(11) NOT NULL, userid varchar(30) DEFAULT NULL, password varchar(20) DEFAULT NULL, name varchar(40) DEFAULT NULL )

ALTER TABLE user ADD PRIMARY KEY (id); ADD UNIQUE KEY userid (participant_id);

ALTER TABLE user MODIFY id int(11) NOT NULL AUTO_INCREMENT, AUTO_INCREMENT=1; COMMIT;

So my id will be just number and auto increment. userid wil be unique.

I created the page by using PHP. And i use following insert command at my page :

do {
        $query = "INSERT IGNORE INTO user(userid, password, name) VALUES ('$userid','$password','$name')";
            $insert = $conn->query($query);

    } while( $insert && ($conn -> affected_rows == 0) );

Are this code can work perfectly to prevent the date conflit ?

Another extra question is, how about if i create another extra page which will insert information 'user' table and can i used the same code at the new page ??