Which 2 table structure is better for photo order storing

[cammac]

When users can drag and drop photos on a webpage to sort their order in photo album, which version to use for storing the photo orders:

 

Version 1:

Table "Album Categories"

AlbumId, AlbumName, UserID

(3 / Family Album / 32)

 

Table "Photos"

PhotoId, UserId, AlbumId, PhotoOrder

39 / 32 / 3 / 1

56 / 32 / 3 / 4

94 / 32 / 3 / 2

92 / 32 / 3 / 3

78 / 32 / 3 / 5

 

 

 

Version 2:

Table "Album Categories"

AlbumId, AlbumName, UserID, PhotoOrder

(3 / Family Album / 32 / 39,94,92,56,78 )

 

Table "Photos"

PhotoId, UserId, AlbumId

39 / 32 / 3

56 / 32 / 3

94 / 32 / 3

92 / 32 / 3

78 / 32 / 3

[Illusion]

Version 1

[cammac]

Any suggestions how to update the photo order when e.g. photo #99 would be dragged to position #1 - that would mean 99 rows would have to be updated in MySQL (instead of only 1 in Version 2)

 

 

[Wildbug]

UPDATE Photos SET PhotoOrder=PhotoOrder+1 WHERE UserId = 32 AND AlbumId = 3;
UPDATE Photos SET PhotoOrder=1 WHERE UserId = 32 AND AlbumId = 3 AND PhotoOrder = 100;

 

You're right, though.  Version #1 may mean more database operations.  It does, however, provide an easy way to get the pictures out in order (by using the PhotoOrder as the ORDER BY column when retreiving photos).  You wouldn't get that functionality with Version #2.

 

With Version #2 you can use explode() to read that delimited string into an array and write your own re-ordering functions.  And, since you're probably not pulling the pictures out in order, but singly (img src="display.php?id=12345"), you might not need MySQL's ORDER BY.

 

Yeah, actually Version #2 might not be a bad itea.  This is one of the few cases where I can see some advantages to using the delimited string, and they're mostly related to performance.

[cammac]

I'm also thinking that with version 2 when I would select the comma delimited string and then go through the comma separated array as I would go through various rows in version 1, then e.g. if I would display 20 photos per album page, I would have to do only 1 mysql row selection instead of 20 rows in version 1, and just limit the comma separated list to 20 first items.

 

So in theory 1 write instead of 99 writes, 1 read instead of 20 reads.

 

Am I correct in my theory? Or is there a downside I'm not seeing.

[bubblegum.anarchy]

Using version #2 and the following query to order the records:

 

SELECT FIND_IN_SET(PhotoId, PhotoOrder) AS orderby, Photos.*
FROM Photos
     INNER JOIN `Album Categories` ON Photos,AlbumId = `Album Categories`.AlbumId
ORDER BY orderby;