How can I insert data into related tables using MySql and PHP

It happened to me the same way and I corrected it like that. Context: I create a support ticket. The Ticket and its properties are in a table, and the messages of the tickets are saved in another. So when creating a ticket, I have to create it in the tickets table and insert its corresponding message in another table. Then, I create the ticket and retrieve its ID at that moment and return it to a function where it immediately inserts the message with the recovered ID.

I had something like that.

Function that creates the ticket:

public function crearTicketController($idUsuario, $asunto, $prioridad, $mensaje, $clase){
            $idu= $idUsuario;
            $as= $asunto;
            $p = $prioridad;
            $c =$clase;
            #primero se inserta el ticket y se obtiene el último ID de la tabla ticket
            $idticket = Datos::crearTicketModel($idUsuario, $asunto, $prioridad, $mensaje, $clase);
            #ahora inserto el mensaje
            $respuesta = Datos::mensajeTicketModel($idticket, $idu, $text, $c);
             if($respuesta==1){
                echo '
                    <script type="text/javascript">
                      window.setTimeout(function(){
                            window.location="panel.php?modulo=tickets&action=ver&id='.$idticket.'";
                        }, 0);
                        </script>
                        ';
             }
             else{
                echo "error";
             }                  
        }

Function that inserts the ticket:

public function crearTicketModel($idUsuario, $asunto, $prioridad, $mensaje, $clase){
        $stmt = Conexion::conectar()->prepare("INSERT INTO tickets (idusuario, asunto, prioridad, fecha, estado) VALUES (:idusuario, :asunto, :prioridad,  now(), 1 )");
        $stmt->bindParam(":idusuario", $idUsuario, PDO::PARAM_INT);
        $stmt->bindParam(":asunto", $asunto, PDO::PARAM_STR);
        $stmt->bindParam(":prioridad", $prioridad, PDO::PARAM_INT);
        if($stmt->execute()){
            $stmt= Conexion::conectar()->prepare("SELECT MAX(id) as idTicket FROM tickets");
            if($stmt->execute()){
                $idticket = $stmt->fetch(PDO::FETCH_ASSOC);
                $myidticket = $idticket["idTicket"];
                return $myidticket;
            }else{
            $respuesta = $this->mensajeError();
            }
        }else{
            $respuesta = $this->mensajeError();
        }

    }

Function that inserts the ticket message:

public function mensajeTicketModel($idTicket, $idUsuario, $mensaje, $clase){
        $id = $idTicket;
        $stmt = Conexion::conectar()->prepare("INSERT INTO detalletickets (idticket, idusuario, texto, fecha, clase) VALUES (:idticket, :idusuario, :mensaje,  now(), :clase )");
        $stmt->bindParam(":idticket", $idTicket, PDO::PARAM_INT);
        $stmt->bindParam(":idusuario", $idUsuario, PDO::PARAM_INT); 
        $stmt->bindParam(":mensaje", $mensaje, PDO::PARAM_STR);
        $stmt->bindParam(":clase", $clase, PDO::PARAM_INT);
                    if($stmt->execute()){
                        return 1;
                    }
                    else{
                        return 0;
                    }
    }

I hope it serves you, that way I solved it and there is no failure. Greetings.

You should be able to get the id you are looking for by executing this after the insert.

If you use PDO PDO::lastInsertId

If you use Mysqli mysqli::$insert_id

In both cases what it returns is by connection to the database so there is no problem that there are other inserts in parallel.

Ref: How do I get the last inserted ID of a MySQL table in PHP?