基于行的动态导航 [英] Dynamic navigation based on rows

问题描述

我正在创建一个产品评估系统，要查看特定产品，请使用以下URL:www.example.com/category?product_id=1.每个页面上的导航只是当前的product_id + 1/-1，因此，如果您要查看我刚才给出的示例URL，则返回到product_id=0，然后转到product_id=2.一切正常，直到我从数据库中删除产品，并且product_id不再存在，它所在的URL才显示空白页.

I'm creating a product rating system, to view a specific product, the following URL is used: www.example.com/category?product_id=1. The navigation on each page is simply the current product_id + 1 / -1, so if you were to view the example URL I just gave, back would go to product_id=0 and next would go to product_id=2. This works fine, until I delete a product from the database, and that product_id no longer exists, the URL it was at just displays a blank page.

将这种导航转换为动态导航以使其转到下一个product_id而不是一组product_id的正确方法是什么?

What would be the correct way to turn this navigation into a dynamic one, so that it goes to the next product_id rather than a set product_id?

推荐答案

的伪代码:

next_product_id = query_value(从产品WHERE ID中选择SELECT ID> $ this_product_id ORDER BY ID ASC LIMIT 1")

next_product_id = query_value("SELECT id FROM product WHERE id > $this_product_id ORDER BY id ASC LIMIT 1")

previous_product_id = query_value(从产品WHERE ID< $ this_product_id ORDER BY ID DESC LIMIT 1中选择ID")

previous_product_id = query_value("SELECT id FROM product WHERE id < $this_product_id ORDER BY id DESC LIMIT 1")

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