Php Mysql表中的自定义自动增量

我的表中有三个客户Id，比如A、B、C。我想创建订单表来管理来自这些客户的订单。我想创建orderID列，以便它必须自动递增并附加cunstomer Id，例如orderID列记录：

A_1  --->A's 1st order,
A_2  --->A's 2nd order,
B_1  --->B's 1st order,
C_1  --->C's 1st order,
A_3  --->A's 3rd order,
C_2  --->C's 2nd order,
C_3  --->C's 3rd order,
B_2  --->B's 2nd order,
A_4  --->A's 4th order,
A_5  --->A's 5th order

这使您可以轻松地插入订单，而无需考虑生成的标识符。创建的附加

行将允许您对它们进行排序，并为它们提供您想要的编号

$result = $mysqli->query("SELECT * FROM `orders` WHERE `customer_id` = 1 ORDER BY `created`");

$orders = array();
while ($row = $result->fetch_assoc()) {
    $orders[] = $row;
}

echo count($orders) , PHP_EOL; // 42

foreach ($orders as $delta => $order) {
    echo "Your order #" , ($delta + 1) , " with the unique identifier {$order["order_id"]}." , PHP_EOL;
}

仅举一个例子。
我希望各个客户的订单id应该是串行的。如果我查询特定客户的订单表，则必须显示序列订单号。。。。。
$result = $mysqli->query("SELECT * FROM `orders` WHERE `customer_id` = 1 ORDER BY `created`");

$orders = array();
while ($row = $result->fetch_assoc()) {
    $orders[] = $row;
}

echo count($orders) , PHP_EOL; // 42

foreach ($orders as $delta => $order) {
    echo "Your order #" , ($delta + 1) , " with the unique identifier {$order["order_id"]}." , PHP_EOL;
}