如何在PHP中连接用户定义的变量并将结果插入MySQL表

I'm trying to concatenate three variables into one variable and INSERT the result into an MYSQL table.

Here's my code so far:

$title = $_GET['title']; 
$colour = $_GET['colour']; 
$shoe_id = $_GET['shoe_id'];

$order_title = $title + '(' + $colour + '|' + $shoe_id');

$sql="INSERT INTO orders(order_title_1)
VALUES('$order_title')";
$result=mysql_query($sql);

Result : $title ($colour | $shoe_id)
i.e. Ara Ladies Reggio Lazer Cut Trouser Shoe (White | 51179-05G) | 12200

At the moment the result stored in the database is zero. I presume this is because I'm using the '+' operator incorrectly, however, I'm not sure what I should be using to concatenate the variables.

What do I need to do to concatenate the variables properly?

Thanks.

Correct way is

$order_title = $title .'( '.$colour.'|'.$shoe_id.' )';

In PHP concate operator is . not +

+ is an arithmetic operator in PHP