构建采购分析功能的企业资源计划（ERP）系统的PHP开发

// 获取指定供应商的采购订单数量
function getPurchaseOrderCountBySupplier($supplierId) {
    // 连接数据库
    $conn = mysqli_connect("localhost", "username", "password", "erp_system");
    
    // 查询供应商的采购订单数量
    $sql = "SELECT COUNT(*) FROM purchase_orders WHERE supplier_id = $supplierId";
    $result = mysqli_query($conn, $sql);
    
    // 解析查询结果
    $count = mysqli_fetch_array($result);
    
    // 关闭数据库连接
    mysqli_close($conn);
    
    return $count[0];
}

// 获取指定商品的采购订单数量
function getPurchaseOrderCountByProduct($productId) {
    // 连接数据库
    $conn = mysqli_connect("localhost", "username", "password", "erp_system");
    
    // 查询商品的采购订单数量
    $sql = "SELECT COUNT(*) FROM purchase_orders o, purchase_order_items i WHERE o.order_id = i.order_id AND i.product_id = $productId";
    $result = mysqli_query($conn, $sql);
    
    // 解析查询结果
    $count = mysqli_fetch_array($result);
    
    // 关闭数据库连接
    mysqli_close($conn);
    
    return $count[0];
}

// 获取采购商品的入库数量
function getInventoryCountByProduct($productId) {
    // 连接数据库
    $conn = mysqli_connect("localhost", "username", "password", "erp_system");
    
    // 查询商品的入库数量
    $sql = "SELECT SUM(quantity) FROM inventory WHERE product_id = $productId";
    $result = mysqli_query($conn, $sql);
    
    // 解析查询结果
    $count = mysqli_fetch_array($result);
    
    // 关闭数据库连接
    mysqli_close($conn);
    
    return $count[0];
}

// 示例用法
$supplierId = 1;
$productIid = 2;
echo "供应商的采购订单数量：" . getPurchaseOrderCountBySupplier($supplierId) . "<br>";
echo "商品的采购订单数量：" . getPurchaseOrderCountByProduct($productId) . "<br>";
echo "商品的入库数量：" . getInventoryCountByProduct($productId) . "<br>";