php mysql大小写语法错误

以下是opencart的一部分：

model/catalog/product.php

if (!empty($data['filter_manufacturer_id'])) {
  $sql .= " AND p.manufacturer_id = '" . (int)$data['filter_manufacturer_id'] . "'";
}

$sql .= " GROUP BY p.product_id";

$sort_data = array(
    'pd.name',
    'p.model',
    'p.quantity',
    'p.price',
    'rating',
    'p.sort_order',
    'p.date_added'
);

if (isset($data['sort']) && in_array($data['sort'], $sort_data)) {
    if ($data['sort'] == 'pd.name' || $data['sort'] == 'p.model') {
        $sql .= " ORDER BY LCASE(" . $data['sort'] . ")";
    } elseif ($data['sort'] == 'p.price') {
        $sql .= " ORDER BY (CASE WHEN special IS NOT NULL THEN special WHEN discount IS NOT NULL THEN discount ELSE p.price END)";
    } else {
        $sql .= " ORDER BY " . $data['sort'];
    }
} else {
    $sql .= " ORDER BY p.sort_order";
}

我正在尝试创建“价格范围”过滤器。这是我的代码：

    //Filter products based on slider price range

    if ((isset($this->request->get['lower']))&&(isset($this->request->get['higher'])))
    {
    $sql .=  " AND p.price >='". $this->request->get['lower'] ." ' AND p.price <='". $this->request->get['higher'] ."'" ;
    }

    //Filter products based on price slider

if (!empty($data['filter_manufacturer_id'])) {
    $sql .= " AND p.manufacturer_id = '" . (int)$data['filter_manufacturer_id'] . "'";
}

$sql .= " GROUP BY p.product_id";

$sort_data = array(
    'pd.name',
    'p.model',
    'p.quantity',
    'p.price',
    'rating',
    'p.sort_order',
    'p.date_added'
);

if (isset($data['sort']) && in_array($data['sort'], $sort_data)) {
    if ($data['sort'] == 'pd.name' || $data['sort'] == 'p.model') {
        $sql .= " ORDER BY LCASE(" . $data['sort'] . ")";
    } elseif ($data['sort'] == 'p.price') {
        $sql .= " ORDER BY (CASE WHEN special IS NOT NULL THEN special WHEN discount IS NOT NULL THEN discount ELSE p.price END)";
    } else {
        $sql .= " ORDER BY " . $data['sort'];
    }
} else {
    $sql .= " ORDER BY p.sort_order";
}

到我的自定义代码：

    //Filter products based on slider price range

    if ((isset($this->request->get['lower']))&&(isset($this->request->get['higher'])))
    {
    $sql .=  " AND (CASE WHEN special IS NOT NULL THEN special WHEN discount IS NOT NULL THEN discount ELSE p.price END) >='". $this->request->get['lower'] ." ' AND (CASE WHEN special IS NOT NULL THEN special WHEN discount IS NOT NULL THEN discount ELSE p.price END) <='". $this->request->get['higher'] ."'" ;
    }

    //Filter products based on price slider

//根据滑块价格范围筛选产品
如果（（isset（$this->request->get['lower']）和&（isset（$this->request->get['higher']））
{
$sql.=“和（特殊情况不为空时，特价情况不为空时，特价情况不为空时，特价情况不为空时，特价情况不为空时，特价情况不为空时，特价情况不为空时，特价情况不为空时，特价情况不为空时，特价情况不为空时，特价情况不为空时，特价情况不为空时，特价情况不为空时，特价情况不为空时，特价情况不为空时，特价情况不为特价情况不为空时。
或者在列名之前使用别名（p.special）

选中这两个选项。
以下是我将采取的故障排除步骤：

确保SELECT子句中包含
特殊
确保不需要使用表前缀，例如
p
在进行SQL比较时，可能不应该引用数字
CASE表达式的格式似乎正确，因此我认为表达式不是问题所在

重要提示：我强烈建议您永远不要在生产环境中使用上述代码。通过获取未经筛选/验证/转义的GET参数并将其添加到查询字符串中，您完全可以接受SQL注入。
错误消息非常清楚：您没有以该名称命名的列。您有名为
spec的列吗ial
？
    //Filter products based on slider price range

    if ((isset($this->request->get['lower']))&&(isset($this->request->get['higher'])))
    {
    $sql .=  " AND (CASE WHEN special IS NOT NULL THEN special WHEN discount IS NOT NULL THEN discount ELSE p.price END) >='". $this->request->get['lower'] ." ' AND (CASE WHEN special IS NOT NULL THEN special WHEN discount IS NOT NULL THEN discount ELSE p.price END) <='". $this->request->get['higher'] ."'" ;
    }

    //Filter products based on price slider