对PHP写库存管理系统中的库存调拨功能进行代码生成

以下是一个简单的PHP代码示例，用于生成库存调拨功能：

<?php
// 假设有两个表：inventory（库存表）和transfer（调拨表）

// 连接数据库
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "inventory_management";

$conn = new mysqli($servername, $username, $password, $dbname);
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}

// 处理库存调拨请求
if ($_SERVER["REQUEST_METHOD"] == "POST") {
    $from_location = $_POST["from_location"];
    $to_location = $_POST["to_location"];
    $product_id = $_POST["product_id"];
    $quantity = $_POST["quantity"];

    // 检查库存是否足够
    $check_inventory_sql = "SELECT quantity FROM inventory WHERE location = '$from_location' AND product_id = '$product_id'";
    $check_inventory_result = $conn->query($check_inventory_sql);
    if ($check_inventory_result->num_rows > 0) {
        $row = $check_inventory_result->fetch_assoc();
        $current_quantity = $row["quantity"];
        if ($current_quantity >= $quantity) {
            // 更新库存
            $update_inventory_sql = "UPDATE inventory SET quantity = quantity - $quantity WHERE location = '$from_location' AND product_id = '$product_id'";
            $conn->query($update_inventory_sql);

            // 插入调拨记录
            $insert_transfer_sql = "INSERT INTO transfer (from_location, to_location, product_id, quantity) VALUES ('$from_location', '$to_location', '$product_id', '$quantity')";
            $conn->query($insert_transfer_sql);

            echo "库存调拨成功！";
        } else {
            echo "库存不足，无法完成调拨！";
        }
    } else {
        echo "库存不存在，无法完成调拨！";
    }
}
?>

<!-- HTML 表单 -->
<form method="post" action="<?php echo $_SERVER["PHP_SELF"]; ?>">
    <label for="from_location">调出库位：</label>
    <input type="text" name="from_location" id="from_location" required><br>
    <label for="to_location">调入库位：</label>
    <input type="text" name="to_location" id="to_location" required><br>
    <label for="product_id">产品ID：</label>
    <input type="text" name="product_id" id="product_id" required><br>
    <label for="quantity">调拨数量：</label>
    <input type="number" name="quantity" id="quantity" required><br>
    <input type="submit" value="提交">
</form>

以上代码示例中，假设数据库中有两个表：inventory（库存表）和transfer（调拨表）。代码首先连接到数据库，然后处理库存调拨请求。在表单中，用户需要输入调出库位、调入库位、产品ID和调拨数量。代码会先检查库存是否足够，如果足够则更新库存并插入调拨记录，否则返回相应的错误信息。

请根据实际需求和数据库结构进行适当的修改。