Custom arrangement

Blackwind

So a user uploads 3 images, and those 3 images are saved in the database.
Now I want the user to be able to drag and rearrange those images. How do I make it so the database remembers the arrangement?

Piranha

I assume that you have normalized the tables and have the images (or links to images) in a table of it own. Then just add a number in that table, when you select use order by to get the order of the images.

Sxooter

Note that if you're gonna add more entries later, and rearrange a lot, it might work better to sparsely populate the order by field in the table. I.e. use numbers like 100,200,300 etc...

Then if someone wants to put a picture between 200 and 300 you use 250. No need to rearrange all the other images each time, and update all the rows.

Blackwind

Thank you for your replies. I still don't really understand how it's going to work.

Re: Piranha
So I have two tables

Images
- img id
- user id
- img url
- img order

Image Order
- img id
- img order

I guess I just don't understand how I would adjust ordering every time....

Re: Sxooter
Yes the images will be deleted, rearranged very often.
I'm not sure I understand, how do I determine that the picture needs to be at 250?

Thanks for helping out guys, I really appreciate it.

Sxooter

Blackwind;10884625 wrote:
Thank you for your replies. I still don't really understand how it's going to work.

Re: Piranha
So I have two tables

Images
- img id
- user id
- img url
- img order

Image Order
- img id
- img order

Not sure you'd need the second table. You could just put an order number in the main table. Make an unique id on user_id and img_order, so you can't accidentally put two pictures in the same number for the same user.

Re: Sxooter
Yes the images will be deleted, rearranged very often.
I'm not sure I understand, how do I determine that the picture needs to be at 250?

Let's say you have 2 images, at 500 and 1000 order_num respectively. The user positions a picture between these two pictures. You would already have the img_id and order_id in the table. So you have the next id and the previous id. Just subtract one from the other, cut that in half, and add it to the smaller one. That's your new number to put into this one.

1000-500=500, 500/2=250, 500+250=750. Insert with that order_id and you've got positioning done. You'd have to make up an algorithm to detect when you're running out of space and renumber all the entries for a user.