PHP逻辑问题
我有一个 sql 表 images，其中包含列 id、imagePath、caption``count。
要查看这些图像，我所做的是，我要求提供页码并查询 iamge
$limit=$page-1;
$sel=$mysqli->prepare("SELECT id,imagePath,caption,count from images".
" order by id desc limit ".$limit.",1");
这会正确显示图像。
但我有另一个函数，它显示数据库中所有图像中的 4 个随机缩略图。对于这些图像，我还提供了一个 href 标签，以便当用户单击该链接时，他将被带到该图像的页面。
现在问题出在这些链接上。 假设我在数据库中有这样的图像
id=1
id=2
id=3
id=4
id=5
要找到特定ID的页码我所做的是
$newid=$idOfTheCurrentImage-($idOfTheLastImage-1);
使用这个逻辑我得到
id=1 page=5
id=2 page=4
id=3 page=3
id=4 page=2
id=5 page=1
如果所有ID都按顺序，这会给出正确的结果。但如果任何一个 id 被删除，这个逻辑就会失败。
还有其他解决办法吗？
I have a sql table images which has columns id,imagePath,caption``count.
To view those images what i do is, I ask for the page number and query the iamge
$limit=$page-1;
$sel=$mysqli->prepare("SELECT id,imagePath,caption,count from images".
" order by id desc limit ".$limit.",1");
This shows images correctly.
But i have another function which shows 4 random thumbnail of that images out of the total images from the database.With those images i also give a href tag so that when a user clicks on that link he is taken to the page of that image.
Now the problem is with those links.
Suppose i have images like these in the database
id=1
id=2
id=3
id=4
id=5
To find the page number of the specific id what i do is
$newid=$idOfTheCurrentImage-($idOfTheLastImage-1);
Using this logic i get
id=1 page=5
id=2 page=4
id=3 page=3
id=4 page=2
id=5 page=1
This gives correct results if all the ids are in order. But if anyone of the id is deleted this logic fails.
Is there any other solution?
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您可以执行以下操作：
添加另一个字段，即“序列号”，这样您就有了对 ($id, $seq_number)，并像使用 $seq_number 一样进行计算。不要忘记在删除时更新序列号字段。
获取数组中的所有 id，并在那里进行计算。在此选项中，计算中不使用 $id 值，您仅使用数组索引。
希望这有帮助。干杯
You could do the following:
Adding another field, a 'sequential number' , so you have pairs ($id, $seq_number), and do your calculations as you did with $seq_number. Don't forget to update the sequential number field it on delete.
Get all the id's on an array, and calculate over there. In this option, the $id value is not used in the calculations, you use only the array indexes.
Hope this helps. Cheers
我建议使用除运行计数器之外的其他东西作为页面分母。正如你所说，它可能会发生变化，或者如果中间缺少一个数字就会失败。
您的图像有标题。您可以从中创建一个“slug”并将其用作页面分母。
创建链接时不再有古怪的数学或模糊的逻辑，也不再有消失的页面。
I would suggest using something other than a running counter as the page-denominator. As you say, it is subject to change, or fail if a number is missing in between.
Your images have a caption. You could create a "slug" from that and use that as your page-denominator.
No more quirky maths or murky logic when creating links, no more disappearing pages.